Forgot you asked how high you could turn it up. A 14b isnt gonna be very productive after 20psi, and thats with a HUGE fmic, I doubt youll have that on your jetski. So I would say 15-16 is as high as youd want to go, with a boost controller you wont be able to turn it any lower than the wasegate is set at which is around 8ish.
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Forged internals with squirters stock. 14psi proof. It WILL be turbo'd, just not anytime soon.