Am I missing something mate - have you got green injectors or are you squeezing 300 out of the yellows somehow? I'm not too sure on the variable option either.

Basically you can up the boost further by chipping again and adjusting the actuator or even upgrading the turbo. Get a pro to advise on this if I were you. Injector wise - Greens are next if you dont have them, then greys like Twellsie. The 2 bar map sensor will have to be upgraded to 3 bar then.

The higher the boost the higher the chance of the head gasket going. Various views on this but head bolts usually need sorting too.

Personally I would get advice from one of our many tuners on here and get a package deal if you really want to up the power. You can fit the turbo yourself first I guess. More power certainly costs more dosh!! Info on the cams would be useful too - they can have quite an influence.

Why not get it checked over first, see if there are any probs with what you have already??

Its a subject we can discuss all day so it will be interesting to see others views on this