Just to add a little to this thread about Throttle bodies...
By spring I'm going to do an actual comparison of a stock TB, a BBK TB and the GT500 with adapter, side by side same day dyno runs and see what's what.
I just got in the GT500 60mm TB which I was going use with a Snow Performance injection plate.
It doesn't fit so I ordered the BBR GT500 adapter and will drill it for the 2 meth jet and use that instead of the Snow Performance plate.
The 60mm GT500 TB has more spacing between inlets than the BBK 62mm so adapter needed. From the picture of the adapter it reshapes the inlet closer, once I get that adapter I want to see if its still 60mm.
The Snow Performance plate will not fit the 62mm BBK without grinding, you need also flip it upside down as you will take less material out of the TB then. This BBK TB has lots of metal you can take away, I found this TB to be a real nice quality TB that doesn't corrode from meth use.
After grinding the meth jet and spacer plate line up perfectly.
A comparison of the BBK 62mm top and the GT500 60mm Bottom.
I just need to get a good stock TB, the Snow Performance Plate fits the stock without any modifications.
Then will test on a boosted 4.6 3v with a YSI-B supercharger.