exhaust question

[^s13^]

n/a is usually louder then turbo cars anyway. more drone.

[b00f]

Im running

Extractors 4-1> highflow 2.5 cat> 30 of 2.5> 30-40cm hotdog > rear muffler
It is.... well fucking loud

If anything, it is too "open" and lacks some back pressure down low.

Do what entran said, custom exhuast, sell your cat back...

[R31Nismoid]

Requiring backpressure is a myth.

[entaran]

Backpressure spools turbo's.

Backpressure is absolutely required for proper N/A performance.

[R31Nismoid]

No it's not. Backpressure is the enemy, especially with turbo charging.
Same with N/A

People that say it hurts their performance on N/A applications say so for a pretty common reason...
They have upgraded the exhaust - but never had the car retuned, so of course it's going to at times not feel like a performance increase and possibly take a performance hit. Turbo cars suffer from this less than N/A.

Backpressure exists for emissions only, as part of a factory car/setup. It has no place in a performance application.

Some reading material...
http://mechdb.com/index.php/Exhaust_back_pressure_myth
http://autospeed.com/cms/article.html?&A=0046

[Kriss]

My r32 lol

dump pipe> straight pipe right out rear bar hahaha

no mufflers, no cat

[entaran]

Let me post it to you from a different angle...

Why modify your vehicle in the vain sense that it's a track car when realistically you only drive it around the suburbs?

Yeah, I fully understand no backpressure on a full track car. But I'd be willing to make the assumption that you don't have one.

[R31Nismoid]

Track or street is irrelevant. Did you even read the articles and information?

Backpressure is not a requirement to make torque.

[mr zed x]

better safe then sorry.

2.5" for good flow and minimal backpressure for the NA.

[SZR0]

running as i bought it. 2.5"up front and 3" towards the back. weird?? my car lacking a lot of performance. might be going for a dyno to see where the problems are.

[Chrisrotary]

Oh geez guys. Its not a hard fast rule thats suits every motor. but there is A LOT going on here. No back pressure can allow a certain amount of the inake charge to slip through on valve overlap (reducing power). so injector timing not pulse width becomes more critical, but then what happens when you up grade the cam duration or LSA or if the extractor is made to compensate. I have mate with a vee 8 who changed extractors and noticed while the it ports were matched the same size about an inch after the flange to the head the pipe diameter was reduced and then flared out again almost immediately. at the collector it was the same thing. It was bottle necked and flared out. He quizzed the manufacturer who explained it increases speed but retains a certain amount back pressure. Optimising flow and horsepower.
I have a rotary and was suffering almost no boost pressure (4.3psi @ 6k actuator disconnected) because of an exhaust blockage. If you free up your turbs on the in and ex side. it spool up quicker and make boost for longer be easier to control and everything. interesting to note f trucks use a butterfly valve to block the exhaust and reduse boost for their turbs. no wastegate at all.
Anyway i fitted a justjap bell mouth dump and from one peice and hiflow ceramic cat to a stagea no ploblem then an fujitsubo cat back and it all bolted up no problem.
Are my posts too long?
oh well.