Personally not keen on putting a charger on my car, but keen to see it done for everyone else...
a few thoughts from when I invesitigated doing it for myself
a centrifugal would offer the best performance, and simpliest operation (works like a turbo, no need for a bypass when the charger is "off", the engine would simply breathe through a non-spooling supercharger)...so in the long run would probably be a cheaper option.
I investigated the option of custom brackets to relocate some of the accessories to make room up front for the charger whilst retaining aircon... Obviously expensive, but would certainly be worth while looking into.
A torque bar to move the charger over to the gearbox side would also be another solution, although its not ideal.
if roots, or screw type positive displacement, consider a water to air intercooler between the blower and the manifold (for the love of god, build a roots blower into the IM - remote positive displacement sucks the big one, they are woefully ineffecient to start with...)
Belt driven pulley but GEARED DRIVE UNIT is a must - belt drive units (the "silent" superchargers) are boost limited.....
Clutch on/off linked to a MAP sensor would be handy...those with aftermarket management could simply plug an output condition to trigger on WOT or on a load threshold, but others wont have this option...so some sort of MAP sensor "black box" solution for triggering the charger clutch on under load would be very useful....
Anyway...thats my thoughts on the matter...good luck with it - hope something comes out of this
