Dino as always 100%++++
TB plate diameter remains the same (stock). What your porting and polishing is the intake part for smooth transition into the butterfly area. Different sanding rolls, variety of sandpaper grits and polishing compound and go to work... polish to smooth high luster! LOL
Some people counter sink the screws, grind down the shaft flush with the plate, radius the rear part of the butterfly and knife-edge the throttle plate itself, but I stay away from that since it can cause drivability issues.
I have done several of these when proven aftermarket TBs are not available and/or way too expensive for the return on HP. Heck, I have even epoxied my Brother's GTO LS TB to build a smoother transition into the intake.
TB plate diameter remains the same (stock). What your porting and polishing is the intake part for smooth transition into the butterfly area. Different sanding rolls, variety of sandpaper grits and polishing compound and go to work... polish to smooth high luster! LOL
Some people counter sink the screws, grind down the shaft flush with the plate, radius the rear part of the butterfly and knife-edge the throttle plate itself, but I stay away from that since it can cause drivability issues.
I have done several of these when proven aftermarket TBs are not available and/or way too expensive for the return on HP. Heck, I have even epoxied my Brother's GTO LS TB to build a smoother transition into the intake.