I'm sorry that I don't know anything about the package you are describing, but I saw a boat last weekend with twin T53's in the Thousand Islands area. These are the sweetest sounding engines I've ever heard. They seem to be pretty practical too. The boat was a 46' skater with a turn-key setup. No hastles... jump in and go.
The reason that I replied is that a friend told me about a website that talks about creative air-flow solutions for the turbines. Appartently with the T53 the air goes in the back of the engine and the exhaust comes out the front. Lots of missed opportunity for performance if it's not installed right. If you're interested I'll dig up the web link and let you read about it yourself. Let me know.