I've had my FRC for about 7 months now and already have the itch for a little more power. Hoping people here can steer me in the right direction. The only mod I have currently is a Corsa Extreme axle-back, otherwise the car is stock. While I want to save as much money as I can during this upgrade, I also prefer quality and reputable brands.

First off, do you see a noticeable gain with an aftermarket intake or is it best to keep the OEM airbox? Before I posted this, I browsed these forums and other pages looking for a definitive answer but had no luck. I have seen a lot of positives about the Vararam and Callaway Honker intakes, but the install is a little more involved than I am capable of doing at this time. The K&N install looks a little bit easier. I've also seen people mentioning the flip-tie mod, but have not looked into the install process for that. I do have plans to supercharge the car in the next couple of years, which would render an aftermarket intake useless. I plan on getting a dyno-tune after these mods are installed, so if people are seeing noticeable gains with an intake versus without I would definitely install one now and sell it second-hand later when I go F/I.

Next question is regarding headers. I am between Kooks and ARH currently. Any noticeable differences between these two brands? I see if I go with Kooks, I would need their X-Pipe whereas the ARH would work with the Corsa X-Pipe. Any longtube headers I buy will be catless.

Lastly, what kind of power have you seen with an intake (or not) paired with a full exhaust? Dyno sheets are a bonus.

Thank you all in advance!

 

The biggest bang for the buck will be adding headers. The intake may add something but almost impossible to measure. One of the members a few years back did a comparison study on a few different intakes and surprisingly some actually had less improvement over stock. You might try searching for intake comparison. I had the Calloway on my 2002 and a Blackwing on 2003 and other than looking like an improvement I am sure they did not add anything.
I have Kooks headers on my 2003 running through Corsa sports and they certainly add something but I cannot give you a definitive number. My 2003 runs so much strong than my 2002 that had Corsa extremes but I suspect the PO might have done a little internal work to help. I have Stainless Works long tubes on my 95 and they were good for a seat of the pants gain. I think almost any brand long tubes will give you a nice gain and will be there if you decide to add a supercharger.
Also if you can find a used intake manifold from a 2001-2004 that will help it breathe more than spending money on an intake.

 

I’m going to throw you a curve ball. If your not going to go with at least a cam then nothing below that will make any noticeable difference. I mean that in a seat of the pants deal. I will sorta take some of that back and say long tube headers and a tune will make a little difference.


Now what will make a difference is a 3:90 or 4:10 gear. That’s the first change I’d make if my car was stock. If money is a factor then buy a gear swap and some speed engineering headers vs Kooks etc. Do they fit as well? No. Do they fit and work well? Yes
Another thought is just do a mild cam. If you can do the swap yourself it’s cheap if not it’s weigh the cost vs the extremely expensive headers that will not give you the same gain.

 

That did not cross my mind, but I like where you are going with this. Will definitely look into options. May have to do that along with headers.

 

as mentioned.. headers best bang for the buck.. cold air intake.. almost Zero..

 

I know this is an old post, the I still think its the way to go;

https://www.corvetteforum.com/forums...post1595889870

 

0 hp increase from an intake alone.

with an intake, headers, full exhaust including z06 catback, I dyno'd at 330 hp and tq.. see the "before" line in the dyno below -- I don't have my stock dyno printout anymore, but iirc, it was around 310.
I've since gone with a super charger and cam and other goodies, that's the other line. but 330ish, maybe a bit more, is what you should expect to see depending on where your baseline is.

Also, why catless? you really don't lose any power from high flow cats these days -- other than the expense, there's really no reason not to include them.
BTW, I do agree with the other comment on gearing .. I have 4.10 gears in mine + 6spd, and love it.

 

You want more power? Go with a intake manifold and headers with
a bigger TB. Hotrod had a article a few years back and MSD and Fast with
a good set of headers and TB were picking up 50 plus hp. The intake was getting
35 hp. Check it out.

 

Last year I did ARH and a Callaway Honker intake, it GREATLY woke up my otherwise stock '03 C5.

 

02 Auto with kooks headers and x pipe Corsa Extreme and K&N, Dyno was 327 up from 285.

 

Main reasons for wanting catless is better flow for when I go F/I and I prefer a little more noise lol

 

modern high-flo cats lose barely any flow and really don't impact sound at all, plus no issues with inspection (I'm assuming your car is >20 years old, and you're not worried about inspection in your state?)
Old-school, yeah, cats were a big restriction. But these days, they really have extremely marginal impact.

 

I was in the same boat as you a few years ago with my 01 Z06. Ended up going with a AFE cold air intake, Billy boat headers, x pipe, high flow cats. Car already had Billy boat mufflers. If I had to do it again with the knowledge now. I would have chosen a different upgrade path. I don't like the AFE intake. Even with the hood seal which is a MUST with any intake designed like AFE, K&N, Black wing is that water will get onto the filter even just from washing the car and next thing you know its bogging down the road because the filter is wet. AFE's cleaning kit is crap and doesn't stay on long. The big bottle you can buy for the cleaning solution is usually out of stock. I tried K&N's cleaning solution and it seemed to degrade the filter very fast. Headers will be very loud if you go the route I wen't. I dynamat'd the entire car and it's still bad. If you get headers either wrap them or get the sealed with the High temp coating because they will melt wires or make them weaker over time. Good Idea to wrap sensor connectors with a high temp wrap to be on the safe side. Good time to change out the engine mounts with headers out as well as adding a remote clutch bleeder.

I have a Vararam, but its collecting dust in my storage unit because with the kit I have I'm guessing a older model as they do seem to improve it over the years is that it would take a lot of time to seal it properly and the way the filter sits just isn't great and was worried I might get some extra crap in there which I don't want. IF I WERE TO DO IT AGAIN. I would still do the intake. Probably Honker. If you are going to supercharge I would just do the zip tie mod until then or push past your fear of not thinking you can install it because you can. Next I would upgrade the clutch/flywheel. I bought my 01 z06 with 21k miles so I'm sure my clutch is fine, but its just not the same feeling like previous cars. If you do headers, 1st gear will become annoying just from the sound when you are trying to be stealthy. Regearing would be another option that is probably cheaper. Seats would be the other thing I wish I did sooner. Don't buy a hand held tuner either. Especially Diablo. Throttle body is another one I think you would have a better feel from as well. Anything that brings in more air will make you go faster, just don't forget about a better fuel pump,pump harness, and injectors to match. I think if you can re gear it, intake and a x pipe with a Z06 exhaust with the throttle body, LS6 manifold, tune you will be happy with it until the supercharger. Skip the headers for now is my advice unless you coat them and protect everything around them and live in a area where you can actually enjoy it and not worry about too much Red and Blue attention. Good luck.

 

High flow cats were a 15rwhp loss on my full bolt on HCI setup. They were the ones LG sells and good quality. That’s a lot of HP IMO.
I have a great tune and you can’t smell any gas etc at idle.

I still maintain a gear will make the most noticeable difference if your only doing mild bolt on’s. If someone isn’t doing a cam swap a Breathless air bridge and intake, Honker or Vararam are the three with the best design.
some Speed engineering long tubes and x pipe along with a gear and tune.
The FRC already has the 3:42 gear so 3:90 or 4.10. It’s expensive at $2200-2600. SE headers and x pipe are $600 for both and intake $500-700.

I don’t know what shop labor cost for a Cam. Going off memory a friend told me 12 hours. The cam and good lifters are about $1000. My guess a shop would be $2500 or so for parts and labor on that.

I have about $1500 into a set of CNC heads and another $300 in studs
$300 in a LS 2 Silver blade TB not ported plus a Fast 92 intake and Breathless Racing CF air bridge and CAI. I also have a Corsa Sport car back no cars. 453whp 401 tq Cam is a BTR stage 3. That cam will clear stock heads.
used some milled 5.3 heads so I did fly cut my pistons.

I did all the work so I can’t do anything other than speculate on labor. Some shops are reasonable and others are down right criminal.
The heads and cam may not be an ideal project for someone but the others aren’t hard for a person who is mechanically inclined.

 

15 hp? for a high flo cat? would love to see the dyno sheets ... I'm sure you're being accurate, but for a modern hi-flow cat, with a proper tune? even so, 15hp, for a non-polluting car .. meh, to me, I'll deal with the practically insignificant loss.
Even before I supercharged, with headers, z06cat back, varraam intake, a tune AND hi flow cats, I was at 330hp. highly doubt deleting the hi flows would have put me at 345, but even so, I'd rather just have a cleaner car, and not have to worry about inspections.


Not sure what you mean by this, just because you can't smell gas doesn't mean it's not polluting.

I'm not sure what your use is, but if this is an "offroad" vehicle (i.e., track), and your track doesn't require cats, then knock yourself out. But if it's a street car, what's the point? It's a minimal amount of loss, even if your 15 hp number is accurate, and with cats in, the c5 is actually a very clean vehicle. I have cats in mine and I'm at 530 hp :-)

 

Great advice! I am leaning towards the zip tie mod to hold me over until I can go supercharged. I don't think I will be able to wait on the headers though as I really am wanting it to be a little louder lol

 

I looked and can’t find the dyno sheets. I’m not sure if I had ever saved them . You can believe me or not. It wasn’t something I did with posting in mind, but they did lose power. If they hadn’t I would have them on the car now vs sitting on my shelf. I spent the money so obviously there is a reason I took them back off.
What I meant concerning my tune is that I don’t smell any gas like you do in most cars without cats. Generally after a drive in a car without them you stink of gas due to a rich idle. You may have mistakenly thought I cared about the emissions aspect. No inspections in my state.
NA 15hp is a not a small amount. If you think about it people will spend hundreds if not thousands chasing 10-20hp here and there.

 

Firstly, the aftermarket intake filters/housings are unlikely to be any benefit until you go to a larger throttle body and a fast manifold. Now the stock filter box is a little restrictive, but the Z06 box cures that with a larger opening. You can pick one up for about $150 used and it fits identically. You will notice a difference above 3500 rpm with the Z box. That airbox has been tested on a flow bench and exceeds the stock tb and manifold flow requirements.

This is my second C5, both M6 equipped. I installed 3.90’s in the first, 4.10’s in my current 2004. Gears really wake these cars up in a big way. But, if you are planning on a supercharger then you won’t need lower gears.

After the gears, I installed 243 heads and a midrange cam (218/226, .587/.587, 114+3). Translation: Slight lope, runs smooth like stock-ish under normal driving. Comes on strong a 2500 and charges hard to 5200+ (I simply don’t push it beyond this). Combined with the 4.10 gears it hauls the mail. I went with a power band for occasional, ok, frequent, mini rips on the street, not for track high end. My advice is be mindful of your intended use and spend wisely.

Long and short of it is you can have a screamer without a supercharger or headers or ported heads. That said, all the aforementioned are OUR FRIENDS and definitely add power! It just comes down to how many sets of rear tires you want to buy, lol.

Just don’t bother with the air filter marketing hype. Also, there’s plenty of satisfied Speed Engineering header owners on this forum, so they are worth serious consideration at less than half the cost of Kooks, etc.

Good hunting!

 

How much money are you willing to spend?