neither can I...

 

although you both have great points in twin screw versus roots id have to say that for a streetable aplication i wouldnt even think about running over 22psi on my LSJ even with the proper forging and porting and axles. so unless you are shooting for a track only, maybe sunday drive 400hp+ cobalt the roots is all you need. and a twin screw wouldnt live up to its full potential in a street cobalt.