Well the bad news is there's no real point in adjusting the wastegate on a 9000 LPT. The 2.3l ones have base boost set at 0.3 bar. Fuel cut off comes in at 0.38 bar. You could try turning the wastegate in one turn, reaching about 0.35 bar but that won't feel much different. I speak from experience here . You'll also not leave much room before fuel cut out comes in. I don't think a Dawes Device or bleed valve will work for the same reasons .
The cheapest way to upgrade would be to get hold of a suitable secondhand FPT ECU together with the APC solenoid and vacuum hoses. That would bring you up to 200hp. In the end I went down the Speedparts stage 1 route
You might also try searching the 9000 forum where performance matters used to be covered.