I have lots of experience with the PT6, and always thought it would lend itself well to boating. However, no experience (yet!) with high performance boating. The PT6 is available in 500 hp up to a little over 1200 hp. IIRC, they weigh about 300 lbs. The exhaust is indeed part of the power section, the duct starts about (guessing) a foot away from the output shaft.