Duane,
I'd call Peter - he'd probably be fine with putting you in touch with someone that could answer those specific questions. Peter told me they managed to design these quieter pipes without costing additional HP. My response to him was that defies the laws of physics
but didn't pursue it.
As for West Chester, PA. get in touch if you're in the area again. Beautiful area to have a Cobra replica - 1,000's of miles of scenic country roads. Biggest concern is deer...
I look forward to hearing FDJake's comments on the quiet pipe's sound when he gets the car back.
Regards,
Kevin