Got some work done on my own car today, experimenting with exhausts and aluminium. First up, 3.5" single, with Virbant mufflers:
Sound clip:
http://vid137.photobucket.com/albums...pscleukp0r.mp4
Then I moved on to a a single 3.5" to the axle, splitting in to dual 3":
The dual is a bit quieter because of the extra muffler.
Overall, I am really happy with both, but will keep the dual on since it is a bit quieter. Entire exhaust weights are awesome. The single comes in at 8lbs, and the dual is at a whopping 10lbs. The pipes on the 3.5" section have a 3 mm (1/8") wall thickness, so plenty material to provide great longevity and durability.
One of the local 370z customers is coming in for fitment/build of these same exhausts, and I hope to offer them for the 370z guys as well.
The single 3.5" will be around $600 and the dual would be about $900 or so. Still have to sit down and actually account for all the parts/materials.
With the 3.5", I hope to make it run all the way to the turbo, the section (about 3') closest to the turbo would be made out of stainless though, as the exhaust temperature is still high.