I used to be... not anymore. Yes, that WSB in the classifieds is mine (well, my brothers). Yes, it's new.
As the ad stated, it's a great turbo for 350-550rwhp. For a daily driver in this range, it works great. Very quick spooling. Not sure the size of the housing, as there wasn't an option when Puis built the WSB. WSB was a WSB. The USB Jason has mentioned, was the big brother to the WSB, designed for the next power level (550-800rwhp or so).
I have seen this turbo on a 650rwhp truck with nitrous. As I mentioned above, my dad, brother and I bought the remaining 10 WSB turbo kits that Diesel Dynamics had when MSD closed DD down. I sold all but 4 - one for me, my dad, my brother and a spare. Now my brother is going to get rid of his truck before installing the turbo, so he wants to sell the turbo. That's the only reason it's for sale.