If I were to go aftermarket on the TB what size should I go with
Thats another "don't bother" mod.lol sorry to just break the bubble every time.
The only thing a aftermarket TB will do is possibly open a little faster to give some "seat of the pants" feel, but only make a few single digit HP for the $400 investment.
we tested late model hemi's and LS engines with everything from a little 85mm, clear up to a 105...almost ZERO difference.
As far as bolt ons that are going to net any power gains... you're looking at a set of headers, full exhaust, a CAI that actually pulls in cooler air...because the tube itself won't net anything, and then a tune to pull it all together.
a handheld tuner with canned tunes isn't worth its weight IMO. you want to get with jay green, or someone to make YOU a tune.
you're taking the above mods, to maybe increase 30-40hp to the ground (generous estimate), all working in unison. And from that point out, you're getting into the cam, heads, or rotating assembly to go chasing "big" numbers.
sorry to be a naysayer...just been there, done that... a tune, exhaust, and mild bolt ons can only do so much.
now we start talking cam swap...there's your 50,60,70 HP gains you're looking for.