TransAm219

I did a search and couldnt find what i was looking for .

I am wondering if anyone ran longtubes and y-pipe w/o cats and then added cats later ?
Did it make a difference in power ( good or bad )

Any other side effects that were good or bad?

Thanks

MonoxideChild

i have a cat after the LT install.

made no difference, but did lower my NOX emissions alot.


so, if emissions is an issue, put the cat in there anywhere it'll help.

if not, then don't.

SlickBlack Z

I dont know if you will find this information conclusive, but I did a test on this recently. I have FLP longtubes with interchangable cats and off-road pipes. When I ran the car with cats, it went 104 MPH in the 1/4 mile(2 passes). Without them, it went 103 MPH(3 passes). My motor is internally stock. Could it be that the motor likes a little backpressure in the exhaust? Not sure, but I put the cats back in regardless.

Spinner

Backpressure is never good.

Be it luck, or false knock from extra noise, it definetly wasnt because of more backpressure that you ran faster with cats.

tryintogofast

I have Jet Hots with two high flow cats running dual 2.5 piping back to Purple hornies with turndowns before the axle. I like it alot. I'm legal and she still goes like a mother.

Spinner

Except that turndowns aren't legal. D'oh

tryintogofast

Ok mostly legal . Jeez laws are to strick. Bah they exit more to the side than the ground I say they're turnouts rather than turndowns. Ha now legal again. What you say now spinner?

Spinner

I say if they dont go over the axle, then your screwed either way

neil350

Yep, has to exit out the back, or some thing out side the side. Speedmiser has a real nice dual cat side pipe set up, and his car still sounds and runs like some sort of angry wooded wet lands creature.

EviLBoX

I made a few passes at the track with both the FLP cats and the offroad pipes and I didn't notice a difference in my trap speeds. I remember a while back someone did a dyno comparison with the FLP cats in and the offroad pipes, I think the car made 5 more rwhp with the offroad pipes. As long as you run high flow cats, you won't notice much of a difference.

tryintogofast

CURSE YOU SPINNER!!!!!

Spinner

stereomandan

Any of you run just use one high flow CAT after the Y-pipe? I know it's worse than dual CATs, but not sure how much worse.

My MAC mids will be using only 1 high flow CAT after the y-pipe. Stock, I have dual CATs and am wondering what the tradeoff is.

Dan

Spinner

I do, one single 3" high flow cat after the y pipe. no issues here. Flows more then both the stock cats combined

stereomandan

Not according to this, which is why I ask.

http://installuniversity.com/install...n11.122001.htm

Dan