Originally Posted by arch4life
stop heating the air. you are pushing the turbo WAY to hard. notice the change in maf g/s from 4-5k, then 5-7k. 5-7k changes almost nothing. maf flow should increase as rpm's increase, all the way to redline.
I thought it was quite common for smaller turbos (VF39's on STI's, TD04's on WRX's etc.) to not have much of a change in MAFv from 5500 RPM onwards. I know the engine RPM is going up, but VE is going down, and the turbo can't force in the air like in the lower RPM's, because the compressor can't maintain that higher pressure towards redline.
I agree about heating the air though, but in the winter with a good intercooler, your charge temps won't be dangerous. So if you don't mind pushing your turbo to the edge then the extra MAFv might be worth it to a person.