which tb
 

i have roughly 400 hp at the wheels (a4) and 150 shot of nitrous. I need a new throttle body for my car, previously it was a 52mm but I'm wondering if would be any worth to upgrade to 58mm or monoblade. I have looked around for awhile now, very mixed thoughts on if upgrading is even worth it at any level. Or what hp level it would be worth it. I'm using a small superchager right now at about 5 psi. So I was wondering if anyone could give me some insight if it would be worth upgrading at 400whp w/ 150 shot. Trying to get to a goal of 500whp w/o nitrous, wondering if upgrading tb would help? Thanks

what mods on the car to get to 400?? and without intake porting your stock opening is 54MM so anything bigger than that is pointless, you can only flow as much air as your smallest opening... lucky for you AS&M has a 54MM TB but they are very expensive. hope this helps!

Since you're running a blower, you might get better responses in the Forced Induction forum.

what have you done to the motor other than nos and supercharger?

just as a note my car makes just under 600 detuned and i run a 58MM (with port matched intake) and i have no air problems at the TB...

A buddy of mine made 1,125 flywheel HP on a Vortech S/C's 383, with a BBK 58mm TB.

When we were tuning my engine on an engine dyno, at a shade under 500 flywheel HP, normally aspirated, running a 58mm Holley, the HP peaked at 77% throttle opening, and opening it to 100% didn't make any difference. That would indicate that a 52mm would support 500 flywheel HP at 100% open.