When I spoke to Micah about happy turbos on the 2.33 he really liked the GTX3582R
"@28 psi we shift it around 8k. 32 PSI get’s stretched to 8500 "
that's on a 2.5 so ymmv
the new gsc springs are rated to 11k+ rpm...
but I would start with this for motivation:
Attachment 27254

