I thought my Titan 875 had an issue too. I bought it brand new , had them pull it back out and install a new one again. Turns out that's just how hydra aster makes them. We are pulling out the Titan and having a prochemEverest 650hp installed instead.
HMs don't dump water at all times. The exhaust diverter is suppose to control the heat without a lot of dumping. It seems to work correctly on my Boxxer 421.