Currently using a 7.8" crank pulley and a 2.5" blower pulley. We do not see any boost drop off until about 6,500 rpm and then only lose about 1/2 to 3/4 lbs of boost. Peak boost is usually around 19.5 psi and might drop to 18.8 - 18.9 psi at the big end of the track. There is no boost drop off in 1st or 2nd gears though. We are using an AFR 225 cylinder head and the 2.2L was all done in at 17-18 psi. We were overspinning it to get that and losing about 2-3 psi at the big end. The 2.8 can deliver so much more air, that this particular engine (at least with the hyd cam) cannot use so much as to have boost drop off even at 6,800 rpm. We were also using the lightest weight hyd lifters that were available at the time and the cam profile allowed for power to still be made (barely) at 6,800 rpm. The coolant hose that goes to the "in" side of the supercharger is fed off of the water pump. We are using a Mezier electric pump, and it has fittings for heater hoses. since we are not equipped with a heater core anymore, we use one of those to feed the supercharger. The outlet hose from the supercharger, feeds back into the front of the intake manifold, where the heater hose would normally have gone. We really had to slow the bigger supercharger down to get to the starting point of 18 psi compared to the 2.2L blower. The nice part of the bigger supercharger is that to get the same boost level as the 2.2L blower is the blower pulley is bigger, and gave more surface area of belt contact, so belt slippage went way down as well. We think some of the loss of boost was due to belt slippage and not due to the blower being a PD design. If you make a hard pass, or dyno pull and see any black dust on the blower pulley, you will also see a boost drop off. Also when we compare data logs, the boost drop off usually goes down as soon as a new belt is installed, verifying that it is really not all of the superchargers fault if there is a boost drop off at high rpm's.