Just got done installing the SSAC/XS headers in the gtp. Started at 10 am and finished at 12 am. The biggest problems I ran into was getting the rear header out (yes the subframe was lowered, however the bolts from the downpipe to the rear manifold and the ones from the downpipe to the catback would NOT budge so I removed it as an assembly) ended up just tearing the factory flex to shreads and it came out. Also installing the front header and crossover was a big pain in the a$$ as well. But all is now installed and well just no catback installed as of right now so I'm running open downpipe with no rear O2 or O2 emulator. Also I didn't wait for the O2 extension so I took the rear O2 and cut the wires off and just rewired the front one and it all works well. An O2 emulator will come soon since the car has the catless downpipe.