Before you click the link I'm giving you, DON'T do it. The results were not good. The TB flowed too much for the range of the OEM MAF sensor.
Besides, the bore of the TB is not the limiting factor on your car from a flow standpoint.
Like that? Yup, been done. No, I don't suggest you do it. That TB is a paperweight now. I still have it.
Shaving the shaft:
Has been proven on many cars here. I've done them for myself, billboost37, jr's3800, harofreak00, and BonneMeMn for testing