AC398

Im going to be getting a full exhaust system in the next 3 months but in the meantime was thinking about unbolting my exhaust after the cat. I wouldnt be gutting my cat and was wondering if anyone has tried this or if this would be a good idea. Im no where near an expert on cars but my thinking was if i dont gut the cat ill still have a enough backpressure and it would increase my flow so more hp and tq. Will doing this increase my hp without any chance of harming my engine, or would it actually just be a bad idea??

KagA152

iTrader: (5)

1. you dont want back pressure
2. it will be loud, and you will get sick of it

you really need to do headers too if you want to notice anything, think of a pop bottle coming off the motor, big on one end doesnt do you any good if its tiny on the other. so youre really just wasting time

urbanhunter44

iTrader: (3)

It sounds like butthole, and moves the power band up by alot. You'll have less low end tq, and more high end HP. But it sounds horrible.

Just save a few bucks and get a nice catback.

And yes, that was the exhaust 'system' on my old '85 Z28.

firebirdjosh

iTrader: (1)

Actually I believe mine had much more torque w/o my catback.

vejatabul

ive done this "mod" before. everyone screams "backpressure!" but he still has a cat. do it. it will sound like ****y borla and will not cost anything. i would not bank on any power increases though.....just do it for the doo-doo sound. not saying that it will not affect power, im saying do it for the dumb-dumb sound. if i were you i would cut it off right before the rear end, at least it will be a little less annoying for your passengers.

DJP87Z28

With you cutting the exhaust off at the cat, expect everyone inside the car to go into a possible deep sleep and not wake up. Just a side effect.

Anniversary-Z-man

iTrader: (2)

NOT recommended at all due to many of the reasons posted above.

jimp2001

I took my cat out, and put a 3" flowmaster drag muffler in its place. put a pipe on the end of the muffler with a 90* bend and went straight out the side. Topped it off with an angled chrome tip, that just happened to line up straight with the body of the car. looked nice, came out right in front of the rear pass wheel well.

CraZ-28

Don't do it. I did with mine when I was taking it to the shop to get my exhaust done. It was cool as hell. 30 minutes later I couldn't stand it. *** I'm glad I have an exhuast on. It extremely loud and just sounds bad(not in a good way either).

xlwhellraiser

iTrader: (1)

I cut my mufflers off and it sounds great. You might wanna concider a high flow cat for the sound that you want though. Trust me. Otherwise you will notice some power gain. Not much but enough to notice on a butt dyno.

FAST RS

A friend of mine did this to his 305 camaro and it sounded like pure crap and very raspy if i remeber i also remeber it poping allot because of a lack of backpressure.

3rd gen V8

Yea i also did this to my car and i thought it sounded ok, or at least for a week. yea its loud and yes i did feel a little improvement in reving and taking off but it has alot of little poping and dosent sound that great, so im putting my flowmaster on it.

urbanhunter44

iTrader: (3)

the popping is created by your car running richer than it should, I.E. an A/F ratio lower than about 13:1 - 12.5.

It's the unburnt gas expanding at a rate which causes it to make the popping noise. Your car will do that until you lean it out, not because of the muffler.

I did alot of research to figure this out, as my car did it alot with the factory tune. So rich it left carbon all over my back bumper.. happens to most LT1s. I've noticed alot of thirdgens tend to run the same way - rich.

DanTheMan_smlk

hahahahha...this is all funny. Currently my car has no pipe after the cat. Its a 305 TPI, and its not that loud (at least not loud enough to get pulled over). It helps with high end power. you WILL get sick of it and the people that call u a r3dneck. I am redoing my exhaust from headers back which is why my car is currently like this. I only drive it when i really need to cause it is kinda loud. You can do it, just remeber u cant put it back on. It will never be as loud as a 4 cylinder with no exhaust on it.

it will pop and rumble when u let off the gas over 40mph or so....its so terrible sounding that i stick it in neutral when i let off the gas

IROCThe5.7L

I drove around 2 weeks with just a y pipe when I put my headers in. I thought it sounded throaty and pissed off. I liked it.

urbanhunter44

iTrader: (3)

yeah ive driven around with an open y pipe.. at idle it sounded crazy scary, and was good for scaring people right next to the car.. other than that it sounded horrible

daStingray

Jimp2001 has it right. His setup will produce a throaty tone.
A better option than just an open cat. With an open cat you get the R's but less throttle response or off the line torque because of backpressure and resonance. Also in our high fuel cost age, ther is less fuel economy. Invest in low restriction everything and @ least a 3" system regardless of where it exits.

DanTheMan_smlk

oh yeah!

87TPI350KID

It's not worth the 5 horsepower. Nuff said.

DanTheMan_smlk

ummmm thats a negative.....

rockit

iTrader: (3)

Thats what im runnin right now and i scare the sh*t out of ricers. i like it but its too loud inside. more bark then bite.


any confirmation on the shifting of the power band with this setup?im curious on that part.

DanTheMan_smlk

i love it when women in SUV's look at their windows rattling when i fly by them....hahaha owned!