It'll sound better and net you more power if you can fit them after the first muffler since that one allows cross-flow like an X or H pipe. Sadly in this car, that is right where the restrictive portion is, but with some careful welding you may be able to replace the entire restrictive part with your cutouts. Go listen to some clips of G8 exhausts without any crossover- it sounds terrible...almost like a misfire or something. You might just wanna replace the first muffler with an X pipe and then cutouts, then go back into the OEM exhaust. The resonators and main rear mufflers will still keep the car quiet and prevent any 4 cylinder drone. If you wanted to get really fancy, Magnaflow has resonated X pipes.