yah you got to do a lot of internal work to get the serious HP out of th NA VG motors. basic stuff would be full aluminum pulley kit, dual MAF setup, exhaust and ECU. im currently the guinea pig for one guy who is letting me test his chips out til he finds a good one to make for all J30s. his cost is much less than Jim Wolf and he specializes in the 300zx as well.
i have a friend with a 300zx that is making 261rwhp on pump gas. he has about $10k in work on the motor though. stroked, slightly higher compression, bigger pistons (90mm i believe) and a crazy tune. currently the highest HP NA in the US that isnt sprayed. he can hang with stock 300zxTT and actually beat them since he doesnt have boost lag.
not trying to be the debbie downer but to make serious power you will need to put money into the VG30DE. im currently at 194rwhp 170ftlbs with full pulley setup, intake filter, dual electric fans and 5spd swap. ECU should have me over 200whp once he gets it figured out.
here is a comparison of the auto transmission to the 5spd
