Does anyone know? I see them advertised for 48MM Throttle Bodys all the time.....

 

I've never seen an airfoil specifiacally for larger than stock throttle bodies. I'm pretty sure you just need to use a standard airfoil and grind some material off. I'm not sure how much but it would be very minor since most of the airfoil isn't in the way of the throttle body bores. It's not like these airfoils are presicion machined. Maybe a standard one will fit and not interfere at all. I haven't looked at mine in awhile so I'm not sure. Every aftermarket larger throttle body I've seen has an integral airfoil so I guess there's no market for a 52mm specific airfoil.

 

Steve91Z28 L98:- Not every aftermarket throttle body has an integral air foil, though most do. See the below linked thread and scroll about 2/3 of the way down for some pics:-
What's the story on Air Foils???
https://www.thirdgen.org/techbb2/sho...=throttle+body

 

i guess myabe my BBK TB already has an ail foil built in. But....I was looking at a few pictures....like this picture here....: http://www.thirdgenresource.com/inc/...l?v=1&pid=1499

See the bottom TB.....the air foil in it is about even with the outter lip of the TB...