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Hello - Does any of you know why the Motion Works Interchangeable Icon 102mm throttle body for the LS engine is not street legal? I don't understand what determines whether any throttle body is either legal or illegal on the street.
I'm looking to upgrade the air intake with the Callaway Honker and also upgrade the throttle body. Any words of advice or recommendations would be a lot of help.
Thank you much!
Anything that affects the emissions system on your engine is subject to EPA rules. Everyone knows if you change something on your car it will immediately cause the end of the earth as we know it so you should definitely never upgrade anything ever. All automobiles used on public roads have to comply with EPA emissions rules as verified at the factory so if you change ANY of it its automatically illegal. EPA has been cracking down on companies who provide tunes and modifications that affect the emissions system so Motion and others are covering their rear ends as much as possible. Depending on where you live it might not matter to you.
Anything that affects the emissions system on your engine is subject to EPA rules. Everyone knows if you change something on your car it will immediately cause the end of the earth as we know it so you should definitely never upgrade anything ever. All automobiles used on public roads have to comply with EPA emissions rules as verified at the factory so if you change ANY of it its automatically illegal. EPA has been cracking down on companies who provide tunes and modifications that affect the emissions system so Motion and others are covering their rear ends as much as possible. Depending on where you live it might not matter to you.
Thank you for your opinion/belief on engine upgrade mods and the effects on the environment, which I'm fully aware of.
I was looking for more of a mechanical/technical response/opinion, and I'm not sure that a throttle body change is even necessary.
The airflow/filter intake system/MAFS in the C5 were designed to meet CA standards and upgrading the airflow intake system along
with a fine engine tune helps make for better performance.
Our MI laws aren't as stringent as CA and I choose to follow/obey the MI laws for the few years I have left to be able to drive.
I do respect your time and opinion.
Thank you
Hello again - I just spoke to a friend who has a lot of experience working on Corvettes and he explained my questions in detail and clarified what you were saying in your response.
I apologize if my response to your answer didn't come across right. I believe I misunderstood part of what you were saying, and I get it now. My friend was able to help me see and understand what you were saying and what I was trying to learn.
Thank you again!
Thank you, Mike. I'm very uninformed about such things. My '03 C5 is my 6th 'vette but the previous ones were '60's - thru '74 and much simpler to work on.
I'm 75 now and my memory retention is about 3 minutes. Lol
I was just listening to others talk and a couple of my friends also have had all types of work done to their 'vette's, such as cam, headers, manifold, exhaust, air intake, etc.
As for me, I just wanted to do a couple of "simple" things and it was suggested that I just do an axle back exhaust, change the cold air intake to a Callaway Honker Intake System, and maybe upgrade the throttle body, change the wheels from 17"/18" to 18"/19" or to 19"/20" or 20" all around, and upgrade the radio/sound system.
My head is spinning after all of the reading and listening to others. I'm beginning to think that other than cosmetic's (wheels, sound system.and exhaust for a deeper growl) I should just leave the cold air intake and throttle body and the rest of the engine alone.
Seems everyone has different thoughts.
Back in the '60's-'70's I was able to pull an engine, swap trans, etc, etc, in a day, but i'm totally ignorant about the last 25 or so years of engine mechanics and changes.
Thank you again for your "hint" that I was overlooking something. You were correct!
Sarcasm and hints can sometimes be hard to interpret when written, especially by strangers.
This is not sarcasm...Going to a 102mm TB is a waste of money unless you plan to change the intake to say a FAST 102 and do heads and cam down the road.
You need an intake that matches the new TB. Otherwise you are just flushing your retirement money down the tubes.
Your best bang for the buck hands down would be to have the OEM TB ported/polished. That married to the Callaway Honker or Vararam, with the 2001+ OEM intake with a tune will net improved throttle response and some seat of the pants improvement that won't break the bank. Although I personally wouldn't want to pay for a tune without an upgrade like cam, heads or longtube headers.
However, if you want a nice little seat of the pants improvement, don't want to open the motor up or do heads, and you can't do headers due to emissions laws...go with the intake, ported/pollished TB, and the tune.
If you really want to wake your car up and not compromise emissions at all....go with steeper gears in the diff. If you have an A4 auto car go with 3.42s. If you have an MN6 car go with 4.10s.
Last edited by Johnny Hardcore; May 16, 2022 at 05:25 PM.
PS...any gains you may net with my above reccomendations (except gears) will be mostly snuffed by bigger, heavier wheels and tires. Aesthetically pleasing maybe...detractors from performance...definitely.
Last edited by Johnny Hardcore; May 16, 2022 at 05:26 PM.
That's the answer I was looking for! Very clear, simple, easy to understand, while showing that you know what you're talking about. You response's have been of great help, and I feel satisfied that my questions were answered without without me needing to continue asking.
I thank you very much for taking the time to help me.
As for me, I just wanted to do a couple of "simple" things and it was suggested that I just do an axle back exhaust, change the cold air intake to a Callaway Honker Intake System, and maybe upgrade the throttle body, change the wheels from 17"/18" to 18"/19" or to 19"/20" or 20" all around, and upgrade the radio/sound system.
My head is spinning after all of the reading and listening to others. I'm beginning to think that other than cosmetic's (wheels, sound system.and exhaust for a deeper growl)I should just leave the cold air intake and throttle body and the rest of the engine alone.
I have had my C5 for nearly 20 years now and my C5 journey has been down an almost entirely cosmetic path and I'll tell you why. Previous to this car I had an AWD turbo 4 cylinder pocket rocket that was much quicker faster than my C5 by a longshot...when it was working.
For as fun as that car was while it was operational, it was broken down far far more than it was up. The car was incredibly fun but also completely unreliable.
I have seen many on this forum and in real life who have upgraded their engines and have either grenaded them or spend all their time chasing down tuning, fuel or any number of other gremlins to keep the car running right. I've seen guys lose interest and leave their supercharged cars to neglect and end up selling for parts because they just don't have it in them to pull the engine or drivetrain for the 5th time.
I'm sure there are also tons of guys who have their 6-700+HP C5s dialed in just right but I would think that they have spent boatloads of time and money to get there.
For me, I wanted my C5 to look good, sound good (inside and out), ride comfortably, have modern amenities and most importantly..be reliable! As a daily driver, I know that I can count on my C5 to start up every time when I head to and from work.
With the exception of wear and tear items such as belts, brakes, fluids and a single clutch change, my car has been completely reliable for nearly 20 years. (with early ebcm exceptions)
I pretty much agree with you also as far as comfort, cosmetics, sound, etc., but I also would like to, when in the mood increase the G-force when I punch it for that "rush" feeling. I 'd like to accomplish that without major engine mods, if any at all.
What Johnny Hardcore was saying made a lot of sense to me and changing the rear gears and maybe polishing/porting the TB would seem minimally invasive while accomplishing what I'm looking for.
Your response was "uplifting" to read (for lack of a better word), while easing the pressure I was feeling to have to do something major that I may later regret.
Thank you for that!
I pretty much agree with you also as far as comfort, cosmetics, sound, etc., but I also would like to, when in the mood increase the G-force when I punch it for that "rush" feeling. I 'd like to accomplish that without major engine mods, if any at all.
What Johnny Hardcore was saying made a lot of sense to me and changing the rear gears and maybe polishing/porting the TB would seem minimally invasive while accomplishing what I'm looking for.
Your response was "uplifting" to read (for lack of a better word), while easing the pressure I was feeling to have to do something major that I may later regret.
Thank you for that!
Hey "spidrluvr" (not sure if you are an Arachnologist or a fan of one of the automobile "spider" variants). I had a pet Tarantula named "Sid the Spider" when I was a teen.
You don't have your car details in your profile (is it an A4 or MN6 etc.) we just know it's an '03 based on your initial post. So being an '03 you already have the better stock intake plennum which was adopted in 2001 for all C5s from the Z06.
A bit more (possibly unsolicited) information to help you on your path....
A4 (automatic trans) C5s require a tune if you change the gear ratio. The MN6 does not. Many with A4s that do a gear change typically opt for a used diff from an MN6 with 3.42s. This is usually the most cost effective and easily sourced way to accomplish this. You can also source new from a trans/diff supplier. It just costs exponentially more. If you don't do invasive work like a mild lopey cam you won't need to upgrade your torque converter.
The tune will be required to update shift points so your trans knows it has a new gear ratio. The tune is 100% a must with an A4 gear swap. Plus a proper tune will extract any leftover power that the hyper sensitive stock tune left on the table. So there is some power to be found just by having it tuned..
Porting and polishing your stock throttle body can be professional done for about $100 to $125. A ported stock TB is much more capable of performance and throttle response than most will lead you to believe. The same can be said about the stock OEM intake from 2001+. I still run my stock ported and polished OEM throttle body and 2001+ plennum on my car and it makes 634rwhp/568rwtq. Prior to the procharger it made 428/398 with heads/cam/Vararam intake and that same ported and polished OEM TB and 01+ plennum.
You can do what you are looking to accomplish both cheaply and reliably. Even if you outsource the work and just stand back to supervise.
Cold Air Intake $400 to $500 new
OEM TB porting and polishing $100-$125
Used 3.42 diff $600-$800 (installation about another $600-$1000 depends on your shop)
Tune $500-$600
All in about what a "nice" set of new wheels would run you.
Last edited by Johnny Hardcore; May 17, 2022 at 11:45 AM.
Hey "spidrluvr" (not sure if you are an Arachnologist or a fan of one of the automobile "spider" variants). I had a pet Tarantula named "Sid the Spider" when I was a teen.
You don't have your car details in your profile (is it an A4 or MN6 etc.) we just know it's an '03 based on your initial post. So being an '03 you already have the better stock intake plennum which was adopted in 2001 for all C5s from the Z06.
A bit more (possibly unsolicited) information to help you on your path....
A4 (automatic trans) C5s require a tune if you change the gear ratio. The MN6 does not. Many with A4s that do a gear change typically opt for a used diff from an MN6 with 3.42s. This is usually the most cost effective and easily sourced way to accomplish this. You can also source new from a trans/diff supplier. It just costs exponentially more. If you don't do invasive work like a mild lopey cam you won't need to upgrade your torque converter.
The tune will be required to update shift points so your trans knows it has a new gear ratio. The tune is 100% a must with an A4 gear swap. Plus a proper tune will extract any leftover power that the hyper sensitive stock tune left on the table. So there is some power to be found just by having it tuned..
Porting and polishing your stock throttle body can be professional done for about $100 to $125. A ported stock TB is much more capable of performance and throttle response than most will lead you to believe. The same can be said about the stock OEM intake from 2001+. I still run my stock ported and polished OEM throttle body and 2001+ plennum on my car and it makes 634rwhp/568rwtq. Prior to the procharger it made 428/398 with heads/cam/Vararam intake and that same ported and polished OEM TB and 01+ plennum.
You can do what you are looking to accomplish both cheaply and reliably. Even if you outsource the work and just stand back to supervise.
Cold Air Intake $400 to $500 new
OEM TB porting and polishing $100-$125
Used 3.42 diff $600-$800 (installation about another $600-$1000 depends on your shop)
Tune $500-$600
All in about what a "nice" set of new wheels would run you.
My '03 is an A4 which you pointed out, makes the diff change to 3.2 more involved than an MN6, but still something that isn't beyond what I'm willing to do.
Thank you for all of the detailed info. You have been a tremendous help and probably saved my foolish spending on things that that wouldn't make a noticeable difference.
I can't thank you enough for the information you have provided me with.
About the "spider" - I've had a few Tarantula's as pets right up until I was in my late 30's. They do make a rather boring pet, but I learned to like/respect them, and
they always served as an attraction and conversation piece to others. About the only thing required of me to care for them was to be sure a steady supply of crickets was available.
I have had my C5 for nearly 20 years now and my C5 journey has been down an almost entirely cosmetic path and I'll tell you why. Previous to this car I had an AWD turbo 4 cylinder pocket rocket that was much quicker faster than my C5 by a longshot...when it was working.
For as fun as that car was while it was operational, it was broken down far far more than it was up. The car was incredibly fun but also completely unreliable.
I have seen many on this forum and in real life who have upgraded their engines and have either grenaded them or spend all their time chasing down tuning, fuel or any number of other gremlins to keep the car running right. I've seen guys lose interest and leave their supercharged cars to neglect and end up selling for parts because they just don't have it in them to pull the engine or drivetrain for the 5th time.
I'm sure there are also tons of guys who have their 6-700+HP C5s dialed in just right but I would think that they have spent boatloads of time and money to get there.
For me, I wanted my C5 to look good, sound good (inside and out), ride comfortably, have modern amenities and most importantly..be reliable! As a daily driver, I know that I can count on my C5 to start up every time when I head to and from work.
With the exception of wear and tear items such as belts, brakes, fluids and a single clutch change, my car has been completely reliable for nearly 20 years. (with early ebcm exceptions)
I've come back to you again because of the things you've mentioned in your last response to me about keeping your C5 on a cosmetic path. I liked what you said you did and I was wondering if you could provide a little advice in the cosmetic area.
I'm interested in changing the radio to a data panel satellite system, install a backup cam, and soundproofing. If you have done these things, do you have any suggestions on any of them?
I'm spinning in circles after reading about sound system upgrades - the type, whether to keep the Bose speakers or not, is sound proofing the wheel wells enough, or is ir necessary to do the entire cabin and wheel wells, etc. Seems everyone has a different opinion and I'd like to hear yours, if you will, including anything else I've failed to mention.
Thank you!
My '03 is an A4 which you pointed out, makes the diff change to 3.2 more involved than an MN6, but still something that isn't beyond what I'm willing to do.
Thank you for all of the detailed info. You have been a tremendous help and probably saved my foolish spending on things that that wouldn't make a noticeable difference.
I can't thank you enough for the information you have provided me with.
About the "spider" - I've had a few Tarantula's as pets right up until I was in my late 30's. They do make a rather boring pet, but I learned to like/respect them, and
they always served as an attraction and conversation piece to others. About the only thing required of me to care for them was to be sure a steady supply of crickets was available.
Although it's not much...the TB porting/polishing, gear swap and tune will have you thinking you bought a different C5. You'll be pleased with the outcome over your vanilla stock setup.
Happy to assist. Especially when I assist others with a unique fondness for most peculiar pets. Sid was a pink toe Turantula. To your point...terribly boring until feeding time yet a fantastic conversation piece. Especially when I had lady friends over.
Looking forward to your report back once you decide the direction you'll go in and execute.
Although it's not much...the TB porting/polishing, gear swap and tune will have you thinking you bought a different C5. You'll be pleased with the outcome over your vanilla stock setup.
Happy to assist. Especially when I assist others with a unique fondness for most peculiar pets. Sid was a pink toe Turantula. To your point...terribly boring until feeding time yet a fantastic conversation piece. Especially when I had lady friends over.
Looking forward to your report back once you decide the direction you'll go in and execute.
I'm interested in changing the radio to a data panel satellite system, install a backup cam, and soundproofing. If you have done these things, do you have any suggestions on any of them?
not sure what the data panel satellite system is, but many people who upgrade the c5 stereo system are happy with a double din conversion. when you go down the DD path, there are some several things you'll need to make it right but when you have it all said and done, it's very satisfying
i would get amplifiers to give your audio some real punch when you turn the volume ****.
I'm spinning in circles after reading about sound system upgrades - the type, whether to keep the Bose speakers or not, is sound proofing the wheel wells enough, or is ir necessary to do the entire cabin and wheel wells, etc. Seems everyone has a different opinion and I'd like to hear yours, if you will, including anything else I've failed to mention.
Thank you!
Ditch the bose! i've not done any soundproofing but those who have, say it's an amazing transformation and is extremely worth doing. i need to get on that one of these days myself.
C5 Throttle body upgrade
