when does the tial 38mm become a restriction. i'll be running a GT35R .63, tubular mani etc etc. i have a choice of either 38mm flange or 44mm flange.. Minimun boost i'll be running will be 20-22psi on pump and up to 35psi on race. The mani design will be like dual wastegates but it will go into 1 wastegate... What do you guys think

 

In your case, I would definately run a 44mm wastegate if you plan on running 20+psi on the street and 35psi at the track. A 38mm wastagate can handle the 20 psi, but definately stressing on the 35psi.

 

I had this same set-up last time but i used a 38mm wastegate. I ran it up to 26psi but i was getting surging like the boost was going back and forth 1-2psi real fast. So i dont know, might do 44mm i guess