You'll best maybe 350 RWHP on the stock twins safely. I bested 327 RWHP on mine at 14 PSI. My mods were FMIC with 2.5" hard pipes, turbo-back 3" exhaust, CAI, JDM 2J 440's, machined USDM 2J cams, 1-piece aluminum driveshaft, Walbro 255 LPH fuel pump, Aeromotive FPR w/ fuel dampener bypass, and...