3 inch for later

[FooFighter]

I'm building up my engine next spring but, wanted to get a few basic parts now, one of which was an Apexi N-1 catback. My car will be turboed next spring so I figured on getting the 3 inch piping. How will that affect my n\a performance? Should I get the gst option?
Will I need a flange or couplink to link the 3 inch piping to smaller stock pipe? (I own a 99gs)

 

[nine9rs]

if your getting 3 inch you should probably wait to put it on until you turbo

 

[Blueheat23]

yea most people believe that any bigger that 2.5 will cause you to loose backpressure...well u know what? fu(k backpressure, engines dont need backpressure, its just something that happens and is a nusense.

Take a strip dragster for example...what does it have for exhaust? A few feet of exhaust tubing, or just enough to get the exhuast gas away from the engine and just enough to keep it hot enough so that it moves its ass out of the pipe. So no backpressure would be the best possible senario for a dragster.

Lets say you have a 4in cat back on an NA motor, your engine poors the exhaust gas into that pipe......now lets keep in mind that hot exhaust gas is good exhaust gas.....well that 4in exhaust pipe is so roomy that it lets the exhaust gas spread out, and when its spreading out its cooling down. now youve got all this cooler exhaust gas in your 4in pipe.....lets also keep in mind that cold air is denser that hot air so the cold exhaust is taking up more room in that exhaust pipe of yours...so now youve got all this dense cold exhaust gas in your 4in cat back that is taking up room while your engine is still trying to pump the less dense, hot exhaust gas thru...see the delema? with all that colder gas blocking the way, the fresh hot gas has a harder time getting out, or the pipe is gonna have a whole lot of backpressure from the colder air. Thats the only time backpressure should ever even be brought up just to let you folks know. Engines dont need it, its a simple by product of cold exhuast gas, just a pain in the ass, kinda like a clogged artery....so no backpressure is good backpressure.

Now this isnt to say you should go out and buy a 1 inch pipe so u can have less space for the exhuast to spread and less space for it to sit and chill and cool down because thats no good either. Too restrictive a pipe and cold exhuast gas is the least of your worries.

So its all about finding the right pipe size for your car, some say its 2.25 for an NA, some say its 2.5, but NONE of it has to do with the engine needing backpressure. In my personal opinion, keep that 3incher for the turbo, all your NT will do with that pipe is cool down and sputter.

 

[justincredible]

Originally posted by FooFighter
Will I need a flange or couplink to link the 3 inch piping to smaller stock pipe? (I own a 99gs)