Paul ( GTStVspec) has 450rwhp in his GTS running a GT30 with stock head and cams but GTR rods and Arias pistons and Greddy intake with the fuel pump at its limit so we dont know if there is much left.The power curve is the best ive seen.
Magic1 has the same set up but stock intake but 256-264 cams,His pump died at 435 but has 365hp by 4500rpm.Both cars rev past 8000 with out the power falling of and run modest boost.Still think 35 is needed for a tru 600 but the average power wont match the 30.