IF IT WERE ME, I would Rebuild the butterfly shaft with Nylon inserts, or another suitable material, and leave it alone.

IF I could not stand the butterflys any more, and thought I coudl get away with removing them(many folks have) then I would pull them, and the shaft, and tig the shaft holes up, and smooth the welds out on the inside. Hopefully someone here who has done that will chime in with some pictures.

Here are some links for you. Not specifically to intake tuning, but...

http://www.phys.unsw.edu.au/jw/Helmholtz.html


more when I get a chance.

87 Raider 4D56td v5MT1
31's..Basically Stock