I've been digging around some sites trying to compare the differences between using a 3in exhaust vs a 3.74in exhaust. The two I've compared so far are the more common Apexi GT Spec and the Apexi N1 (single). What I've come up with is that the N1 is better for mid range and the larger GT Spec is better at high range hp. Now, does this only matter when running a certain whp range...say 250+? If I wanted to eventually run 400+whp, will the N1 hurt me in the long run or vice versa with the GT Spec. Reason being is that I've seen those commonly used exhausts as well as the HKS Hi-Power go for a $400-$600 range for a full catback system. But, what about the higher prices systems like JIC's Magic Bullet and Blitz Systems? Is there really any benefit to running a higher priced, Titanium system. Or even the mid level/prices GReddy systems that I find not a whole lot of people run on SR's. Or does it eventually boil down to personal preference. Just looking for some usual info, keeping flaming/bashing to a minimum

 

first off, let me introduce you to the metric system. the apexi n1 is 80mm, and the gt spec is 95mm there is no need to convert over to inches, when i first looked at the topic, 3.74 inches, i was like, " who in the hell buys 3.74 inch piping. however, i quickly multiplied it by 25.4 and realized you were talking about the gt spec before even opening the thread. the metric system is what these motors are based on, lets keep everything that way.


the larger exhaust the better on a turbocharged vehicle. any piping diameters that may increase exhaust velocity all has to do the exhaust manifold , turbine housing, and turbine wheel. from the turbo back, make it as big as possible to make the pressure differential from before turbine wheel to after turbine wheel as great as possible.

 

Sorry about the sizing part...just went off of some vendors sites'. Is there a point were you exhaust is too big...for instance Glen was running a 4in exhaust on his car, and it was ridicuoulsy loud..but Im sure it served it's purpose. Where do you draw the line between turbo sizing and exhausts? Is there a formula or calucator I can look at? Im shooting for 400-450whp, dont know turbo sizing yet, so I wouldnt know what size exhaust is best for my setup. I do plan on running of course an aftermarket exhaust manifold which would allow me to keep my a/c, but Im assuming it all comes down to what turbo I choose?

 

Who makes a 90mm downpipe though?

 

More than 80mm(3-inch) exhaust is usually overkill IMO

 

Look up Apexi GT spec down pipe

 

if you want a really big exhaust, just run open downpipe

 

Well that makes sense doesn't it

 

i have yet to see the apexi gt spec downpipe listed as 90mm or whatever.

+1 with charles' statement....


except 3 inches is technically 76 millimetre.

 

I think the dp is listed at 60.5mm