what is with all this mud slinging. this should be considered a debate not a boxing match.

bigger is some what better. an increased flow of air.
But, you can still need the right size pipe with a little bit of back pressure unless you have a fuzzy logic boost controller (I think that is right). something that will know to open early for the boost spikes you will get with an over sized exhaust.

also when your exhaust pipe is sized right, your exhaust will flow straight and smooth. With an over sized pipe it will tumble, creating turbulence.

In my opinion 10-20% bigger than your turbine outlet is a good size.

Also, if you are running an open waste gate like me, your exhaust pipe will not need to be that big. I have 2.5 on a sohc turbo and with the open waste gate I get plenty of boost spikes especially when the weather is cool.

Well that is my 2cents

 

That's what I was getting at, about half a dozen posts back... Everyone's talkin smack about "Porky Smell", I'd be happy to see him be wrong, but (with the exception of Dee, who was still talkin smack) no one had any numbers to through out there. If it's just "My friend has a 3" and his car feels faster" then that is wrong. it feels faster because your butt wants it to be. Like I said. I'd love to see an actual dyno.

 

True that 3" N/A exhuast is a no brainer , BUT all I was getting at, is that a bigger exhust on a Turbo car is better then a smaller one by comparrison.

AND, there is not going to be that much of a difference between a 3" OR BIGGER exhaust WITH A TURBO.

 

you want zero backpressure, but you want velocity (n/a or turbo). a turbo... that spits out a lot of air.... needs to be able to get rid of it asap... thus open-downpipe or 3" piping is good.

 

SIRKID,

If you want the Greddy canister...go to a muffler shop and have 3'' piping made for it..I did that the total costs was about 120 bucks with hangers/welding.....cheaper than a thermal!.....now if I can only find someone that makes a bigger downpipe for the 18G greddy kit.