Just wondering... what's everyone's thoughts on this? How much power would I be losing if I did it? I can't afford the high flow cat at the moment.

 

with a turbo back its from the turbo back i took my cat off and just have a straight pipe i only kept the resonator. from the resonator i is just a y pipe and 4 in tips

 

lol yes I know what a TBE is. I am asking if people run a cat-back with a downpipe, but have kept their stock cat and how much power would be affected. In other words.. how much power could I be gaining by getting the high flow cat or cat delete pipe.

 

There would be quite a bottleneck going from 3" pipe to stock piping and cat to 3" pipe again. I'm sure it'll free up some flow, but you'd be much better off keeping the same size piping throughout.

 

what's the stock piping? 2.5"? Does anyone out there make a 3.5" exhaust or is that big just pointless?

 

I'm pretty sure that 3.5in diameter piping is overkill. 3in piping is more than enough to support any amount of horsepower that is offered thus far. I am interested to know the gains from removing the stock cat when a CBE is already installed. Im not a fan of black powder all over the back of my car.

 

3.5" isn't pointless at all. The only person I know of is ETS. They have V1 exhaust with a 3.5" center section, but it necks down. I believe gains of full 3.5" over 3" will be more apparent in the gt40r hp range.

 

Keeping the stock cat will negate any power gains from the exhaust system.

 

Get a test pipe, it's cheaper!


You will probably get more gains from a test pipe, than the o2/downpipe, since the gains from the o2/downpipe may be negated by leaving the stock cat on.

Your best bet for the most power without buying a full TBE is probably getting the o2/housing and a test pipe and keeping your stock catback.

 

^+1

Not sure if the gains would be totally negated, but why leave a potential bottleneck on when it is usually the cheapest part of the exhaust system?

 

You would definitely be minimizing gains buy running through a stock cat. The stock cat is smaller (I think its actually 2.25" on a 9! might be wrong but its surely smaller) and it has more cells then necessary to clear emissions. Your best bet would be to buy a 3" certified cat (gruppe-s I believe has a new one but it might be for the evo 8/9 only) if you want to stay legal or a cheap test pipe for all out performance and noise. I have been pulled over for multiple things, but never my test pipe on my loud Buschur exhaust, *knock on wood*.

 

just get rid of the cat i just got rid of mine and it sounds awesome i posted a video on one of my last threads check it out


http://www.youtube.com/watch?v=U4_qUNL2DAo

 

i run a QTP DP w/ecutout and avo CBE with the stock cat in place. pretty quiet till i hit the switch

 

I have a cat back with the cat and intend on eventually getting the AMS O2/Downpipe combo and keeping the cat, maybe getting a high flow.

 

You can run the stock cat, but... this will restrict flow greatly.

Thanks,

Michael