Alpine: you might say "theres always someone who will say otherwise" but imo all your doing is quoting wild power figures, with no backup, and when someone queries it with FACTS your sticking your head in the sand.
The fact that a VF35 will be flat out at 350hp is no secret. Its common knowledge, and if you post the question on any scooby forum, or google it you'll see that for yourself. It will flow somewhere between 425 and 460CFM at 18 psi. This is a fact, not made up crap.
The conversion between CFM and BHP is around 1.5 so 460cfm is around 310hp.
What your trying to say is that a turbo thats only physically capable of flowing 310hp, is making 420hp. Surely you can see why this doesnt add up mate? If the VF35 can make 420hp, why would people swap them out for hybrid "20G" turbos when they want 400hp?
I couldnt care what reputation the tuner has, they CANNOT extract 420hp from a VF35. Its impossible. Its like me saying i'm making 300hp from my k03 on the 1.8T. If they've told you they have, then they're lying.