Was wondering what the difference between the stock mitsu turbine and optional HPD turbine wheel is that Blouch offers on the 440XT is. Spooling RPM? Boost capacity?

Am starting to consider a turbo upgrade for my '11 WRX, and have seen this one pop up a few times and my tuner recommended it for a decent spool time and power increase over the vf52. No access to E85 before anyone recommends it, was going to go that route but the pump near my house closed 2 months after I moved in.... any other turbo suggestions? Looking at sti style turbos as well.

Invidia TBE
305wtorque/295whp on Az 91