If I wanted to bump an 07 XKR up to around 440 - 480 HP (500 max) is that possible and/or advisable? If I was going to do it, are we talking about a total engine redo or are there bolt on mods that can get it there? Will things like an Air Filter even help it that much?

 

I've got K&N air filters, ECU Tuning Group tune and pulley and a custom cat-back exhaust. +60hp easy... It's more then just added horsepower, the whole character of the car has been morphed. Enjoy