|the numbers seem low. Correct me if I'm wrong but you're running E85 whereas I'm on 93. I have the Z1 GT535R turbos which supposedly are the same as the JWT 530BB.
Previous owner had the motor rebuilt + the turbos and a tune, supposedly dynod at 489WHP @ 18psi which is only ~6hp shy of your numbers at 20-21psi. From what I can tell, the shop where it was tuned has a Mustang dyno which supposedly reads lower than a Dynojet (meaning my 489whp should be higher on a Dynojet).
I wonder how much higher your numbers would have been without having spark blowout. Or maybe the 489whp number I got from the previous owner was bullshit...I don't think it is though.
Side note - we also have a similar boost controller, I have the Greddy Profec B Spec 2...but I don't know the first thing about tuning it. I touched it once and tweaked something...haven't touched it since. What settings would you recommend if I'd like to target 18psi again? They might still be fine, I just don't know where they should be.