I'll try to answer some of your questions as I am in the same boat as you are. There have been a couple "attempts" in twin turboing the crossfire with no results ever posted. So far some of the claims I have seen is that the ecu will handle about 5-6 psi of boost. Although I don't believe this because of the 17lb injectors that are on the car could not possibly handle that load. TVT has found a set of larger injectors that will work , but I'm sure they will be too small for what you want to do. The SRT has a comp ratio of 9:1 and is taking up to 22 psi of boost from the factory SC. Our NA's have 10:1 so they won't handle as much. I'm trying to find a different con rod or piston to drop to 8:1. I want to go with a powerdyne supercharger because it has the lowest boost temps that I have found so far and are capable of 40psi. As far as tuning is concerned, I know split second has had success boosting the v8 version of our block using piggyback computers to tune. They are basically a different version of Apexi's SAFC which I am going to use to tune mine. I think the bottom end is capable of 600hp. How long it will hold together , who knows .
Now get ready for the fun part of this forum. The doubting Thomases will now try to destroy your will to live and tell you you should have bought a SRT6 etc etc etc.... Also 99% of the replies will have nothing to do with your post and will erupt into ***** envy fights. Shoot me a PM if you want to discuss this more in depth.