Originally Posted by mkoesel
The GT4 uses a stock S65 (might be different exhaust tho - not sure).
The GT2's P65 racing motor does have a flat plane crank though.
The GT4 uses an all titanium Akrapovic exhaust which adds a 20 HP and weighs some 23kgs(est 50 lbs) less.
I didn't know the GT2 (ALMS) P65 has a flat plane crankshaft, thanx for the info.