i would not run more than 4 lbs boost with the cast piston,its way past a ring gap issue,the cast piston is to weak and it will break,supercharged engines need forged pistons .

Ring gap is an issue on ANY motor that sees more combustion heat than expected.
Cast pistons, however, are delicate and can't tolerate being beat on.
Plenty of economically priced forged pistons out there.

Your choice.
MC