We did some testing in a sled pull application and found it to be lazy on the bottom end and had a hard time keeping up on it at the other end of the track. (sled Pull Application)
This was with a few different housings and housing needed created some drive pressure we do not like to see. I believe they have made some adjustments since the version we where trying last season. As for BB vs. JB we use as much as we can per applications a BB over a JB. All of our new turbos that we tested last season ended up being BB. We have seen a BB be more forgiving then a JB in over spun applications. The 2.8 and the 3.0 chargers have almost instant spool up and are based off a GT42R cartridge.
Man I hope this isn't the case. The turbine did look pretty small when I had the housing off. I wonder what one of the new Bullseye S475r's with their race cover and 87mm turbine would work like?