i bought a pvc end cap that fits perfectly in the intake/turbo coupler. then i put a %$#^# valve (tire valve stem) in the "end" part of it. i couldnt use a bike pump because if there are any leaks, the air leaked out faster than i could pump.

a lot of air compressors are loud too, much too loud to hear an air hiss. one thing you could do is get one of those tanks that you fill up with an air compressor, and use that. you could probably find one with a gauge on it for a set psi. it would probably be very silent too. the soapy water is a good trick too, just spray it on welds, couplers, and the bov flange.

if you have a boost controller, dont worry about blowing your head or too much pressure, because the wastegate will open at the certain psi level.