But lets say you go lighter wheels, pulleys, clutch/flywheel, rotors and you should get that back.

Easiest way to check CL is buy a AFR gauge. If you drop out of 14.5 fast, like a 1-4 drop, you're in open loop. You can do CL all the way to redline. Just press the throttle easy.

Bu then we're not comparing apples to apples anymore. If you mad those changes to the setup without the SC, then the MPG would be even higher which would mean you are still losing some, relatively, with the SC right?

True. Just saying info I guess

It's good info, we all know we'll lose mpg with a SC, just trying to get a better idea of how much for people who do care about that as well. That is good info, though to help out if someone lost more than they expected, though the clutch/flywheel is only for manual drivers.