We did a pair of turbochargers for a twin 3406E engine race boat on lake michigan. His requirements were 1000hp per engine and lightning fast response. You boat guys sure make it tough on us turbo guys
Luckily SIS (cats parts program) made it a little easier on us as they at least give SOME info on the turbochargers.
Can you measure the turbine wheel? There are quite a few flavors of turbine for the HX55 turbochargers. A simple turbine upgrade can do wonders.