I personally owned the Stillen exhaust when I owned a G35.
After adding the BERK HFCs, the stillen exhaust rasped and was embarrassing.

So i did the Magnaflow x pipe muffler mod.
Basically you remove the stillen x pipe and their resonators, then install the magnaflow x muffler where the stillen x pipe used to be....thats it

forget if it was the 12468 or the 12568

alot of guys have done this mod with success on the BORLA EXHAUST and on the HKS replica exhaust

This mod got rid of the rasp, made the exhaust even deeper, and seemed to give a little more performance

 

or you could always rock it out like this last car...

http://www.youtube.com/watch?v=mr6JC...layer_embedded

HELLA JDM lol

 

Its called the 'Bosozoku' movement in Japan

 

I built a custom exhaust for one of my customers, and it worked out well. I also have the same on my car and really like it. It is a bit louder than stock, no drone at all though yet it flows very well with the straight through Magnaflow mufflers:










The idea was to keep the OEM look and improve performance/flow.

 

That APS looks really good. Here is a picture of the DC
system that I got. Very similar I plan on keeping this
one.

 

Correction on what I posted earlier. Not an x-pipe, for the DC.
I think the APS either, looks like they go straight through to
the exit.