On Your Left,

I can answer your last question about the PV. The reason many of us purchased them was that the PV was built and dyno-tested on a VX. Gains of horsepower were documented. If you want to see information on the PV and testing stats before and after installation of a PV, go to

http://tonemonday.com/Storage/pv_muffler.pdf

You will need Adobe reader for it.

The search function on "PV" will bring tons of information on it. I think most who have a PV product are really happy with it. The louder sound was a boost for many but a real detraction for others.