Not enough power? Too boring? Completely ignore all the above advice save loads of money, and try this 2.5 conversion available in the U.K.:
http://www.agdesktop.com/wallpapers%...201024x768.jpg
Or perhaps be content you have a very capable, reliable, and sexy sports car with more than adequate performance, & go get your thrills in the bedroom instead!
BTW, I have owned 3 TVR's all with more than 300bhp/tonne, and now have a Z4 2.5i, -performance isn't everything, most drivers don't even get
close to the limits of the car (on a twisting back road) before "bottling out" IRMC.