i was using mine with no hole too. it held boost great. had it on the dyno, showed a steady 10psi all the way till the end, then dropped slightly by less than 0.5psi. then i discovered i had a boost controller module connected to my unichip so i removed the turbotech, hooked the stock solenoid back up. set it to 10psi on the dyno, and it held the exact same boost pattern. needless to say, the turbotech was doing an excellent job. the only difference being, once i was back on the road, i discovered that the very slight lag on changes was now gone.
edit: also, one less defect in the engine bay