Sport Compact Car magazine had a really good article on this back in early 05 (may 05 maybe?) but you're right to sit and think. its not as simple as it sounds. if a supercharger geared to spin 6 psi is hooked to a turbo set at 10 psi, you're not gonna get 16 psi. you gotta think about static pressure ratio's, the compressor efficiency of both compressors, and and the engine. the best way to do it is to have a one way valve between the supercharger and turbo. that way when there is a vaccuum between the too then the supercharger is working but the turbo hasn't spooled up fast enough to supply more air than the supercharger can ingest. once the vaccumm between the two dissappears,, then the turbo is pushing more air than the supercharger, the valve bypasses the supercharger and the turbo is spooled and blowing compressed air straight into the intake manifold. you also have to consider the fact that say: air comes in at 70 degrees and gets compressed by the turbo and then its...for example 120 degrees afterwords. then it goes through the supercharger and gets recompressed and even more heated. the system is hard to intercool after the supercharger w/o getting completely heat soaked very quickly. the idea is to intercool the turbo then feed it into a roots blower but it is still jamming hot ass compressed air into an engine. and the fact that the air coming into the engine before air bypasses the s/c doesn't get intercooled