how much boost

also would i need to fit an oil cooler or would it cope thanks

Before you get going, GQs suffer from overheating with a turbo, so oil cooler, and make sure your radiator etc is TOP condition.

6psi, 8psi my car was no different to std.. Im running 11 now, and will try 14 when I get a fuel aneroid fitted.

Get it done by someone who knows their bleep , fuel pump etc.. I didnt and had to go elsewhere in the end anyway..

Also 3inch exhaust is the go.

9 psi is about standard, then go up when you modify bits, such as exhaust.
3" exhaust will remove the back pressure, but mainly the heat to reduce overheating.
The aneroid, Also known as an air fuel ratio is an extra part on top of the injection pump that delivers the air/fuel mixture in exactly the right quantity, so you get the max power at all rev ranges, and reduces the black smoke when you plant your foot.
Your looking at big dollars with the aneroid, as the whole pump needs to be removed and recalibrated, but well worth it.
A mate had his gu dynoed at 150hp at rear wheels!
Talk to West End Diesel for a quote. Tell them your a mate of Mick Christie, as i used to work there and youll get a good price.