I got a quote a few months ago from a semi-local shop willing to do an engine overhaul to install a Votec Supercharger and got quote $7,500 +/- $1,000 (depending on hiccups). Would include boring to 3.2L, new cams, new crankshaft, lightweight pulleys, and custom fabrication for the SC install and fine tuning included. Estimated +65% increase in current performance (because custom cams, bigger pistons, etc.)... they said though, i risk outperforming my transmission and rear differential before 5k miles before they either need to be repaired and/or upgraded... so... overall... it would take maybe $10k+ to actually get REAL performance out of this engine... i would rather invest in the S85 (V10) personally and just do an engine/tranny/differential swap if i'm going to spend THAT much... at least then, i would still be N/A, have a BAD ASS exhaust note, and would likely stand the test of time because no forced induction...
though... the high pitched whine of a SC is pretty sick too