I have just spent this afternoon fitting a STI 5 cooler to my 94 WRX. Boost is controlled by a Blitz Dual SBC. On old cooler boost held fine and only crept a max of 1 psi.

After first run boost was instantlty higher on all settings, only to be expexted with better flowing cooler I expect. However on a 10 PSI setting from 4k revs to 6.5k it will now creep up by 4 psi. Strangly on higher boost setting of 15 psi it only creeps to 16 psi. Very strange. I have altered gain from low to higher seting and it does not change things.

Any ideas ?

Clive