HI there,
I think you're overcomplicating the bypass valves... Remember the supercharger and the turbo are sequential, so no matter when you turn the supercharger off, you will lose at least 1/2 your boost, no matter of the turbo is doing. Mine is programmed to turn off at 7500, but that's more of a safety/rev limiter precaution than trying to get it out of the way. It's also controlled by throttle position, so if you want to run turbo-only, then just use less than 50% throttle. It does turn off between shifts, but so far that has not been a problem.
I use no ABV (removed it), and my supercharger bypass valve is a dumb flapper. No electronic controls on it at all.
The supercharger shouldn't mind recieving hot air from the turbo, because it won't be for much time, so there isn't much chance to heat up the supercharger lobes, and the turbo does not have to supply huge amounts of boost, so the air should not be too hot. Use 2 intercoolers if you can, but in my case, there was no room.
My first attempt had the throttle plate before the turbo and before the supercharger and before the intercooler. There was a tiny bit of throttle lag, it made kind of a *pop* sound when you opened the throttle and air filled the intercooler and pipes. Yes it could take a while to get back down to idle, but fortunately, the TPS has an 'idl' wire that makes the ECU cut fuel when rpm>2500 and the throttle position switch is closed.
I have done both turbo>supercharger and supercharger>turbo. I don't have a preference, but move the throttle plate close to the intake valves.
Anyway the twincharged 20v is installed and running. I just buttoned up all the computers last weekend, and am cleaning up underhood wiring. I was using the deleted supercharger ABV as a blowoff valve, but today I got a Greddy-clone blowoff valve, which will make me change some other plumbing to make it fit. It now runs COP ignition, no EDIS parts. It's coming along...
Twincharger
http://www.geocities.com/twincharger/
