The stillen y pipe combines into a single exhaust, whereas the x pipe remains 2 pipes: a true dual system.

^ right. So, there is more flow with an x pipe. But how much flow does this car need? Remember that most cars need SOME back-pressure, or it can actually hurt performance, specifically torque.

It only combines into a single exhaust for about 8" then splits back to dual. At some point all "Y" or "X" exhausts connect then branch back out. I'm still not getting where the difference is I guess.

http://www.stillen.com/image.asp?/pr...ges/504355.jpg

Exactly, it combines into one pipe. That's not a true dual. What's the good of having dual pipes if it combines into one? It's a bottleneck in the flow of the system.

Right on... Well I guess the only "true dual" system would be 2 individual pipes running from 2 downpipes back to 2 mufflers then out. Screw it. I'm not trying to start crap, I have just always wondered and now I guess I have my answer

I didn't think you were trying to start crap, it's a legitimate question.

I forgot to address your point of X pipes connecting and splitting. When you look at the x pipe in the above pictures, the two pipes connect, but remain two individual pipes. If you're wondering why they connect at all, which a lot of people do, it's to balance the exhaust so it all flows out at the same rate. This is important for a consistent sound and better torque.

But as I already touched on, to me there is a difference between an exhaust going into one pipe and then splitting into two separate pipes, as opposed to two pipes that never combine into a single pipe. I guess I just don't see the difference between 8" of single pipe, or 5'.

Not trying to sound anal, I just don't think a single pipe really meets the spirit of "true dual."

I can see your point there. I'm glad you didn't think I was trying to crap on you. I really just never understood ya know. Now that you have made a little more detailed explanation and I have looked at the pics a little closer, I can see what you mean. Either way, I'm going Stillen lol

Here is a pic I found of the Stillen catback together if this helps (if this is the wrong catback system, someone tell me). You can see the X on the GTM and the Y on the Stillen here...

Thats the same pic I tried to post on an earlier reply. That's where this whole thing started with the "true dual" I appreciate it though. Now the pic is up and everyone can see the difference.