They will never see 500RWHP - I was already squeezing them pretty good to make that power. They are basically 25#/min and 446RWHP is actually really high for their specs. On pump fuel they just barely make 400RWHP which is consistent with 25#/min X2. They are a decent upgrade/replacement for stock turbos, ballbearing, inexpensive. But they'll only do 400RWHP on pump fuel/ 450RWHP on race fuel.
We are now working on a 550RWHP BB setup which should be available within a month or so.