You increase the boost by changing the wastegate.

You can either swap the spring (involves opening the can which might not be easy) or adjust the length of the rod.

I have done it by cutting the rod and welding in a threaded adjuster like one end of a turnbuckle. You can also just thread the rod and use a locknut rather than welding and risking cooking the wastegate seals.

Shorter rod = later opening and higher boost.

Or you can do what the riceboys use, two bleed valves in series from the pressure line with the wastegate line tee'd from between them. Adjust the bleed valves to adjust the boost.

An EGT gauge is a great idea if you're playing around with fuel and boost. I fried a turbo on friday, the first warning was the EGT reading 880C. <img src="/forums/images/graemlins/angry.gif" alt="" />