I have the Vast stage 4 with 1 piece steel flywheel on my GT28 car "17.5lbs" which is perfect in weight, not to light or heavy. Go with the 17.5lber or the stock one trust me on this. The awe setup will never hold the power your looking for.

I don't no your full GT setup but the GT2871 is very lazy. There's other options out that will make more overall power without being near as lazy etc.