the only way of hitting 300hp+ in the K03 2--ps is with the k04 turbo conversion from the Ed30/S3.
FWIW i know my car @ stage 2+ could keep up with a stage 2 Nurburgring edition VXR with IC, intake and exhaust. He reckoned he had 296hp, and i had around 270-280hp.
stage 1 GTI 240Hp
stage 2 GTI 260hp
stage 2+ GTI 280hp
Stage 3 (K04 Converted GTI) 330-360hp
Stage 1 Ed30 280-300hp
stage 2 Ed30 300-330hp
stage 2+ 330-360Hp
If your tuning, you need the ed30 really, the extra buying cost will be cancelled out by the tunability. Also better residuals