Disadvantages of 3" exhaust?

[Yurgle]

how the exhaust gas will behave if you install 2.5" headers/OP/FP and a 3" catback ?

i mean, if the entire system have the same diameter the pressure is likely to be the same, but in the catback, where the diameter increases, the pressure drops. Would it help suck the exhaust out of the engine?

[Poodles]

Originally Posted by Calum

Don't egr systems reduce cylinder temps?

Correct.


Also, exhaust backpressure doesn't exist and anyone that uses the term is a crackpot that doesn't have even a rudimentary education in fluid dynamics...

[Chad86]

After reading this thread, I hope to gain some insight as to whether it would be worth it to fit a 2.5" exhaust onto my 3" setup to tone down the volume. Currently 2.5" header then 3" all the way back.

Originally Posted by stockysnail

My tuner slapped on my innovate w/ intercooler and 70mm pulley with my JDL UEL catless headers, Nameless 2.5 OP/DP resonated/catted, stock midpipe, and nameless 2.5 w/ 5" mufflers. I got about 250whp. He slapped on the complete AVO 3" to the JDL header and he got about 20whp more, so in my experience the 3" got more power. However the setup (nameless I mentioned) was a little too loud going up the long hill I had to go up every day so I took off the stock midpipe and nameless axle back and put on a Nvidia Q300 instead, which makes hills ok to drive up again without being too loud. The car is still loud when giving it a healthy dose of pedal, but when not on it I get a slightly louder than stock noise. The nameless does sound better however, but I couldn't take the hills anymore.

One advantage of an exhaust that's not overly loud is I can hear my supercharger whine much easier now, which is more fun hearing anyway.

[Freeman]

Originally Posted by Chad86

After reading this thread, I hope to gain some insight as to whether it would be worth it to fit a 2.5" exhaust onto my 3" setup to tone down the volume. Currently 2.5" header then 3" all the way back.

I swapped from a catless UEL header with 3 inch header back to a catless UEL header and a 2.5 inch over pipe and front pipe with 3 inch catback. It's so much quieter.

[mrk1]

Why not put the money towards the turbo? I made 300 whp through the stock mid pipe.

[fumanchu1]

Originally Posted by cortrain

Doesn't sound TOO loud, a catted header may help me for noise as well. I need that for emissions here, I figure I can swap out the front pipe with my stock catted one easy enough come E-test time.

As per power gains, I know they will be minimal until I get a tune and header.

Thanks for the responses guys!

I have a catless jdl header and catted Perrin 3in FP into 3in perrin CB and my car came from Ontario and apparently passed emissions... just saying.

[Chad86]

Originally Posted by Freeman

I swapped from a catless UEL header with 3 inch header back to a catless UEL header and a 2.5 inch over pipe and front pipe with 3 inch catback. It's so much quieter.

SOUNDS to be the issue is the 3" diameter. Probably going to choose to switch to the Greddy Supreme SP and stock 2.5" OP/FP. I guess I will have to cut my losses with the JDL 3" pipes and catback. Anyone with turbo, I will have parts for sale soon.