Ahhhh, now I understand. I just couldn't imagine dropping hundreds of bucks on a pulley and Anderson power pipe and not even feel a difference, heck you might even lose a little power. But considering your tune is all jacked up and your going to retune, blow thru is a great option. But i will say that a good tuner can tune it draw thru just fine. Mine is spot on and I am running the stock paxton stuff. If/when I build a motor and raise the power levels I will go blow thru with a custom power pipe.
If you are going to take it to a good tuner it may be best to set it up with the way he is most comfortable though. So I guess all in all, it's up to you.
Is the pulley/pipe necessary? Nope! But it can't hurt. Maybe Greg can get those pics up. And you can switch to blow thru, run the rigged/custom/free pipe and leave the pulley alone and see where that puts you with a good conservative tune. I honestly could only imagine a 1psi increase. if that, with a power pipe on a stock motor and 10psi pulley. Just back out timing a few degrees and you can be fine.