IIRC the s362fmw moves more air than a out of the box s366, but it costs more also. If I was goin strictly tow rig, like a 2wd dually, I'd go 175/30's with an s362 for sure.
362 is ~64 lbs/min and 366 is ~ 72 lbs/min (not sure if this is the new updated design I thought I heard about)
The 366 looks like a great 400 whp turbo based on its map. Still playing around with the equations/parameters though. The hardest part is deciding on where to go for the exhaust side when picking a turbo. I know it all depends on driving style and intended use, but the intended use for these trucks can be so broad at times.
That Turbo Talk thread was great. It really solidified my obsession for compounds (long term goal) due to HRT's comments.