prelude2.2

i have 2.5 from the collector all the way back on my lude with no cat just a resonator i got tuned already and i did 196whp 156lb tq i was curious i think my car is to loud and raspy i want to put my cat back on but its smaller then 2.5 inches will it affect my tune alot and also do you think it will sound smoother out the muffler or will it sound worse since its smaller in diameter?

ZekeComa

You have to use the same size.

prelude2.2

doesnt answer my questions lol

Enzo15

It will cause back pressure just after the header. If your states emission laws are not strict, and you can have whatever cat you want on your car, then look at summit racing for a cat that has 2.5 in/ out. Having one will affect the tune slightly, but not enough to need a retune. Do you have a resonator and what muffler?

schmitty915

iTrader: (1)

Having a cat will greatly reduce, if not, eliminate the raspiness depending on your entire setup.

However, the stock cat will not bolt up in place to the test pipe. (If you have a test pipe.)

If you don't even have a test pipe, you will have to modify the exhaust to accept an aftermarket catalytic converter with a 2.5" inlet/outlet.

Tight-R

It's not that hard to buy a HF cat and weld on a couple flanges. I doubt it'll be anywhere near restrictive enough to ever notice a difference on or off a dyno. There's a huge misconception on how much a cat really effects the flow of the motor. Taking them off just makes the car sound like ****.

Tight-R

Not to sound rude BTW, it's just such a waste to ditch a cat. Yea, ditch the stock one for a larger diameter one, that makes sense. Ditching it all together is just useless, especially if you're only making ~200whp.

prelude2.2

yea i hate the sound bad the one i have @ home is a two and a qtr but my entire setup is two nd a half im running try y headers so yes i have to modify my setup but figure save $$ nd use wat i have even tho its smaller or order a 2.5 in nd out and stay same size?

schmitty915

iTrader: (1)

Go with a 2.5" inlet/outlet. The hytech replica header has a 2.5" collector so if you put a smaller one in between that and the rest of the exhaust, it will create a bottleneck effect because it's trying to flow a larger volume of exhaust through a smaller diameter pipe.

prelude2.2

Right on ill do that then