Unless he's gong to get REALLY serious with his turbo selection, I don't see how any custom kit is going to be able to best a hard spun S-Trim backed up with spray? There have been guys who’ve knocked down over 600rwhp alone without the aid of nitrous to fatten the torque cure and cool the air charge.
Even if you manage to size it for a compressor that'll best a set up like that in horsepower and torque, it’ll all be at the big end under WOT. It'll be a nuisance to drive on the street for the most part. The power band would be finicky and sluggish under vacuum and lower boost levels then violent and short when it really starts moving some air.
It’d make a great race set up, but its not how I envision a daily driven street car?
...and again, this isn't just about what set up would make the most power, or would be the most drivable. In the end he's still starting over with the custom Turbo kit. Where he's only adding nitrous to his existing S-Trim.
In any case, it probably doesn't matter now, since making this thread he's put his S-Trim up for sale.
I just prefer it over a centri S/C. But IMHO you cannot beat a nice twin screw! It makes a small enging feel like a huge engine and the sound.. the sound is just 
They’ve all got their draw backs man. Turbo's are no less a pain in the ass than any blower I've seen. More so in my experience when the miles start piling up.
