I will be adding a Magnaflow Catted X-pipe along with a Magnapack Cat back system. Will I need a tune for that? I will be adding a C&L cold air kit and will get it with the Diablo, but I want to wait until I have more miles on the car (only 238 now). However, the exhaust I want to do right now, the stock sound just does not do it for me. Also, what are good prices for these 2 pieces. I saw the catback in Steeda's catalog that came with my Tri-Ax, but it is the retail price. Can you get this stuff cheaper? Thanks in advance