A comparison - my Rb30 has just been fired up. Stock bottom end and stock RB25DE head new rings bearings rod bolts and N1 pump. Sinco manifold (similar to 6boost) Greddy copy FFplenum, HDi i/c, GT3540 with .63 ex, stock throttle body+ fpr, 550 injectors, synapse 50mm w/g , Link G4, venom cat and 3in exhaust now at 9 psi (to be tuned to 18 - 21 psi) limited to 6500: