racecar

I plan to rebuild my exhaust system when I install my new L92 short block.
This year I will go to the track for a few road race days, but mostly I will run through the gears on canyon roads, and cruise on summer nights. I'm thinking of putting Cat Converters on just to be almost legal, and so it does not smell so bad at every stop light. It may make it a little quieter also, it's pretty loud inside with Flowmasters. What is the downside to running Cats, other than extra heat, and a few lost HP. Do the 3" aftermarket cats really cost very much power? Anybody have experience, or dyno numbers with and without 3" cats...

c0ncEpT

iTrader: (4)

You will lose roughly 5-10hp by adding cats. Totally worth if it your trying to get rid of rasp or the raw fuel smell IMO. But I'm sure others will jump in and tell you to man up and just go catless.

racecar

Thanks for the input. I was thinking the same thing, could be as small as 5-10 hp with 3" cats. For 20 minutes on the track, does a cat get red hot??
Every car that I have taken the the track had the cats removed.

KW4life06

iTrader: (12)

Yup. Man up. Go catless. Its like going commando, only real mean can handle it

HWI

iTrader: (2)

I prefer cats, I hate rasp. A set of high flow cats isn't gunna cost you much power anyway and you can just run a cut out when you want the little bit of extra power.

Arctic2002ss

Well, the shop that did my cam and tune was surprised at the numbers the car made with cats. I would guess that I would gain no more that 5hp by losing them. Plus my exhaust setup would probably be too loud for me without them. Oh, I run my car on the road coarse and have not noticed any problems with them.

Arctic2002ss

I was happiest with the sound of my car when set up like yours. The cam made it a little louder than I would like though. Plus it seems to scare off potential races when I let off next to them at high RPMs, lol.

Siphon

iTrader: (7)

I've heard some people argue that removing cats will give you NO increase in HP. Will only make your exhaust louder and more raspy.

KW4life06

iTrader: (12)

Depends really on bow do you're exhaust. Usually the catbacks get pretty raspy without cats. TD's on the other hand can have lots of tone without nearly the rasp, generally. All depends on the mufflers too.

KW4life06

iTrader: (12)

I highly doubt that. Removing high flow cats would give you smaller gains, but they are still a restriction. In no way do they help promote exhaust flow over a flat inner surface of regular pipe

twitchtwice

iTrader: (12)

when i put my full exhaust on i used cats, duals, and straight thru bullet mufflers, now i dont have numbers but my car felts a huge increase EVERYWHERE across the board. so i dont see how my cats are restricting it that much.

GODUCKS

My personal experience
https://ls1tech.com/forums/generatio...s-h-c-ls1.html

2002SS#1811

My current set-up is below. I am going back to a high flow cat. When I did the Heads/Cam the car is a bit loud. Atleast that was what my area finest told me when I went by him at about 60mph. Got off with a warning ticket but if I don't do something it will be a long summer. Larry over at Speedinc told me loss will be minimal and only really noticeable on the dyno. I will still have a cut out if I feel the need. Hate to say iot but I will not miss the fuel smell either, Good luck...

racecar

Great input from everyone. With the cam, heads and intake, I have enough HP to scare myself on the track, and to smoke street tires in first and second. With this new L92 bottom end, I may net the same power as the LS6 motor with no cats, so I'm going to try it with them, and see if I like the way it sounds, and smells. I have been running on the street without for a few years, I can always remove them if it kills power and sound.

Domsz06

iTrader: (2)

on the topic of cats, for those of you that smog, do you have any issues with places not letting you pass if you have high flow and or no cats?

I'm moving to Houston, so any and all advice would be appreciated.

tee-boy

iTrader: (8)

8 horsepower

integraxtc

iTrader: (11)

I'm going to have cats on my TDs to kill sound, rasp, and smell.

A few hp lost, sucks but the benefits outweigh my perceived loss.

2002SS#1811

Passed smog with high flow cats before. No sniffer or visual here in Illinois. They just check for codes and functioning system.

A good tune and no problems...

Domsz06

iTrader: (2)

thanks for the info.

That's what I have heard.

My bro has high flow and they caught them on the visual. I guess I gotta decide what I'm gonna do. Could always keep it registered in a state that doesn't require it.....

cdubbzz

iTrader: (11)

+1 for cats