Not a rip off, a lot of sport owners use the borla reps. Both the reps and the gen items are unequal length and the sports are equal length out of the factory so you WILL lose power (between 10/15bhp) - they're fitted so the car sounds like a turbo model.
Hope that helps
imho, the money would be better spent on a second decat, deresonated centre pipe and decent back box