I got my guy at the dealer to order it for me as they are an authorized BMP dealer. I seem to remember the cost being around $350-375 plus install. I think my total including installation was around $500.00 even?..
btw: I already had the Supersprint Magnum exhaust on my car and I recently installed the X pipe and it actually sounds a little more subdued than before. It is not at all (at least with the SS exhaust) loud. Just alot more of a "raspy" sound, especially under hard acceleration! Very sweet sound!
I am certain it would likely be much louder than mine if you have the Dinan exhaust installed.