I have 263rwkw @16-17psi on a slide high flow... but its at its limits. We did manage 278rwkw ringing its neck on the dyno. I have supporting mods with stock internals:
CAI system, s/steel intake, turbo back exhaust, splitfires, greddy plenum, 90mm TB, 550 injectors, FPR, Walbro 255, Cam gear, FMIC, Oil cooler, Aftermarket ECU running MAP sensor, Profec E-01. Still running standard fuel rail though... My mods were aimed at higher power though and some possibly not necessary to achieve the 260rwkw!
Car is currently undergoing a slightly bigger turbo , ext gate (plumbed back not screamer), 6 boost manifold and cam shafts.... whilst a spare engine is currently going through a forged rebuild in anticipation of the big bang.....lol .... although during the track day the car had no blow by (well the tiniest amount smaller than 5c) ..... might last longer than anticipated! Compression & leakdown been down on the weekend hopefully.