Adding LT's, cats or catless??? Need some advice...
Thread Starter
Melting Slicks
Joined: Sep 2009
Posts: 2,180
Likes: 233
From: Minnetrista Minnesota
Adding LT's, cats or catless??? Need some advice...
Just got a sweet deal on a set of LG stepped LT's from a forum member. They are brand new in the box, and he ordered them catless. With LG, you can add cats without having to buy the whole X-pipe.
So, now I have to make a decision, buy the cats for $300, or run them catless. Car is going to be bolt on only (AFE, ported TB and intake) plus the headers and running stock NPP. I live in Minnesota so no emissions to pass.
I am assuming the catless option is going to be louder and maybe a few more HP. Is the sound going to be obnoxiously louder, or just a tad louder. And I have heard running catless you can get a lot of fuel smell in the cabin, any truth to that or is more in the tune.
What do you think, spend the $300 or run naked...
So, now I have to make a decision, buy the cats for $300, or run them catless. Car is going to be bolt on only (AFE, ported TB and intake) plus the headers and running stock NPP. I live in Minnesota so no emissions to pass.
I am assuming the catless option is going to be louder and maybe a few more HP. Is the sound going to be obnoxiously louder, or just a tad louder. And I have heard running catless you can get a lot of fuel smell in the cabin, any truth to that or is more in the tune.
What do you think, spend the $300 or run naked...
Safety Car
Joined: Sep 2006
Posts: 4,364
Likes: 408
From: Greer, SC
As far as cat/catless, it was the smell that bothered me with catless cars I've driven. Some don't even notice but I'm very sensitive to smell.
You also don't mention your goals with your car or if it will be tuned. In my opinion, with a stock car, headers will make the car sound a lot better but don't expect big gains. The LT1 manifolds are pretty free flowing. Even with a tune, gains will be mostly due to the tune not the headers.
I'm at 700 RWHP and I went with cats even though they may melt due to continued use of Methanol. You will not pick up much, if any, HP without cats vs High Flow cats.
Good luck with your build.
You also don't mention your goals with your car or if it will be tuned. In my opinion, with a stock car, headers will make the car sound a lot better but don't expect big gains. The LT1 manifolds are pretty free flowing. Even with a tune, gains will be mostly due to the tune not the headers.
I'm at 700 RWHP and I went with cats even though they may melt due to continued use of Methanol. You will not pick up much, if any, HP without cats vs High Flow cats.
Good luck with your build.
Thread Starter
Melting Slicks
Joined: Sep 2009
Posts: 2,180
Likes: 233
From: Minnetrista Minnesota
Yes, going to be tuned for sure. With forementioned bolt ons, LT's, and tune I am hoping to see 450 whp. Would love to hear from some of the guys running catless on the LT1 for some real world experience. Sound and smell are my two main questions...
Drifting
Joined: Dec 2012
Posts: 1,630
Likes: 203
From: MI
I know this is going to sound pretty dumb to some people.
The only way I would run catless is if my exhaust shoot flames like those twin turbo lambos on YouTube.
Other than that I would go cats allday because of smell.
The only way I would run catless is if my exhaust shoot flames like those twin turbo lambos on YouTube.
Other than that I would go cats allday because of smell.
Cruising
Joined: May 2015
Posts: 10
Likes: 1
I ran "catless" on my G8 and was horrible to sit in traffic or even at a stop light. I got the LGs with the cats and have no issues with the smell. A couple HP is about the loss and that isn't enough to worry about as the weather will gain or lose you more...
Former Vendor
Joined: Dec 2011
Posts: 1,475
Likes: 29
From: Salt Lake City Utah
I'm with them 
If you were FI I would argue that the catless would be worth consideration but in your application, I think you'll welcome the reduced smell and so will the people around you.
All the best,
Jared Royce
888.308.6007
If you were FI I would argue that the catless would be worth consideration but in your application, I think you'll welcome the reduced smell and so will the people around you.
All the best,
Jared Royce
888.308.6007
Thread Starter
Melting Slicks
Joined: Sep 2009
Posts: 2,180
Likes: 233
From: Minnetrista Minnesota
Tks Jared, that is the conclusion I came to, going to run cats...
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Instructor
Joined: May 2015
Posts: 119
Likes: 6
From: San Antonio TX
Have you installed them yet? I'm in the middle of doing mine. The LG headers DO NOT include an extension to run the rear O2 sensors. I spent the better part of today removing the passenger side header. You will have to drain the oil if you have a dry sump car to get the new passenger side header in.
Unless you REALLY enjoy working on your car, pay someone to install them.
Unless you REALLY enjoy working on your car, pay someone to install them.
Safety Car
Joined: Sep 2006
Posts: 4,364
Likes: 408
From: Greer, SC
Have you installed them yet? I'm in the middle of doing mine. The LG headers DO NOT include an extension to run the rear O2 sensors. I spent the better part of today removing the passenger side header. You will have to drain the oil if you have a dry sump car to get the new passenger side header in.
Unless you REALLY enjoy working on your car, pay someone to install them.
Unless you REALLY enjoy working on your car, pay someone to install them.
Go Canes!
Joined: Dec 2009
Posts: 5,975
Likes: 329
From: Boca Raton FL
St. Jude Donor '11-'12-'13-'14-'15-'16-'17-'18-'19-'20-'21
As far as cat/catless, it was the smell that bothered me with catless cars I've driven. Some don't even notice but I'm very sensitive to smell.
You also don't mention your goals with your car or if it will be tuned. In my opinion, with a stock car, headers will make the car sound a lot better but don't expect big gains. The LT1 manifolds are pretty free flowing. Even with a tune, gains will be mostly due to the tune not the headers.
I'm at 700 RWHP and I went with cats even though they may melt due to continued use of Methanol. You will not pick up much, if any, HP without cats vs High Flow cats.
Good luck with your build.
You also don't mention your goals with your car or if it will be tuned. In my opinion, with a stock car, headers will make the car sound a lot better but don't expect big gains. The LT1 manifolds are pretty free flowing. Even with a tune, gains will be mostly due to the tune not the headers.
I'm at 700 RWHP and I went with cats even though they may melt due to continued use of Methanol. You will not pick up much, if any, HP without cats vs High Flow cats.
Good luck with your build.
the fumes. Definitely put cats.
4th Gear
Joined: Feb 2016
Posts: 4
Likes: 0
From: Palm City Florida
My advice is to have the car tuned and just have them turn the rear O2 sensors off. Due to the O2 sensors being moved back, they will not get as warm as they need to. Eventually you will probably get a Check Engine light. It may take time, but most times you will wind up with a CEL.
Instructor
Joined: Jul 2017
Posts: 127
Likes: 32
From: Shelby Twp Michigan
LT headers
Just got a sweet deal on a set of LG stepped LT's from a forum member. They are brand new in the box, and he ordered them catless. With LG, you can add cats without having to buy the whole X-pipe.
So, now I have to make a decision, buy the cats for $300, or run them catless. Car is going to be bolt on only (AFE, ported TB and intake) plus the headers and running stock NPP. I live in Minnesota so no emissions to pass.
I am assuming the catless option is going to be louder and maybe a few more HP. Is the sound going to be obnoxiously louder, or just a tad louder. And I have heard running catless you can get a lot of fuel smell in the cabin, any truth to that or is more in the tune.
What do you think, spend the $300 or run naked...
So, now I have to make a decision, buy the cats for $300, or run them catless. Car is going to be bolt on only (AFE, ported TB and intake) plus the headers and running stock NPP. I live in Minnesota so no emissions to pass.
I am assuming the catless option is going to be louder and maybe a few more HP. Is the sound going to be obnoxiously louder, or just a tad louder. And I have heard running catless you can get a lot of fuel smell in the cabin, any truth to that or is more in the tune.
What do you think, spend the $300 or run naked...
My main problem with this install was that A significant rattle in the exhaust under light load acceleration from approx. 1200-2000 rpm. Hope you don’t experience it. I fixed it by putting a rubber isolator between the
exhaust and the cover plate.
Safety Car
Joined: Nov 2005
Posts: 4,381
Likes: 939
From: Huntsville Alabama
just installed kooks and catless. I don't smell anything abnormal... but I also have not had a catted car in the past 15 years they are all heads cam, or blower LS cars. guess its all what you like. I like them loud, and with the Npp you have the best of both worlds.
Drifting
Joined: Feb 2001
Posts: 1,768
Likes: 297
From: Plano TX