SIMPLE, The reason you felt less power was because you were more than likly dumping boost straight out your BOV, the small "vac" line, is also a BOOST line, when your on Boost, this applies boost to the LOW pressure (atmospheric) side of the BOV piston, there is a light spring in there too to help keep the valve shut, the boost through the small line and the sping are STRONGER than the boost and the BOV stays shut. now, when you disconect the small line, there is no balancing pressure when on boost, the boost applies to the face of the BOV piston, overcomes the spring pressure and open the valve, Less boost, less power. when the small line is hooked up, and you close the throttle, the small line is AFTER the throttle butterfly and will be in a Low pressure (or vacume) state, this applied to the back of the piston, along with the boost, which now has nowhere to go becasue of the closed throttle butterfly, overcomes the spring pressure against the piston in the BOV, and dumps boost into the intake, UNTIL the boost falls to a point where the spring can override the boost and close again. this is a normally functioning BOV. it is quiet and help prevent RAPID deceleration of the turbine assmbly, although the turbine is Light, it is spinning VERY fast, in high boost, up around 200,000 rpm or more, when you dont give anywhere for the boost to go, the compressor becomes a big brake and slows the turbine fast, this can put alot of strain on the shaft, bearings and wheels. If I were running up and over 15psi, I think I would use a Good, high volume BOV, remeber, they only dump EXCESS boost. Under 15psi, to stock cars, ( BA-BF Falcon) the turbo has poven to be very tough little piece of gear, and I think No BOV, when disconected corectly, would help with throttle response, but do it at your own perile. My experiance with turbos is limited to LARGE earthmoving gear with 4 turbos that are large enough to put your head in the inlake, thhey dont like suddon stops when they are making 40-50 PSI boost. they fly apart, and take out $400-500K engine along the way. I only have about 20 years of playing with these thing, so take what you will from my comments.