Gents
I just fitted supersprint cat less headers and did ESS catless header tune with their handheld flash unit
They loaded a 95RON map and a 100RON map
You wont get much additional power from axel back exhaust, maybe 5-8hp
The above has made unbelievable gains, car is a monster now compared to OEM
I am waiting for Akrapovic to launch their rear axel back system in May, merely for weight saving, aesthetics and sound.
The SS cat less Dps have made it sound really throaty. You can hear the turbos spooling up pretty loudly. At low RPM sounds like a turbo diesel
Hamann is making same power as me and changing the rest of exhaust doesn't aid in removing any other restrictive sections since there are only one set of cats in the V of the engine behind the turbos, and you won't believe how restrictive they are. Cant even see light through them, in reckon they are like 800 cell LOL