@bracemaker I have never had one fail, but the 97 Mastercraft is my only experience in a ski boat. I also like the fact that we skied in really cold water when I lived in PA during the fall and spring and the heads and block were not exposed to the really cold water, which occasionally caused a cracked head in the old days. Haven't heard too much about that anymore.
My other experience with heat exchangers were in 41"Apache with with a pair of 850's and aluminum heads. We used them to keep the saltwater out of the expensive blocks and heads. Never a problem there either and they took some hard abuse.
@shaneh The 6.0 Indmar in Jimbo's Mastercraft jump boat I'm skiing behind until my new Malibu gets here doesn't feel like it's low on power. Plus the loud exhaust makes you feel like your at the racetrack. Although, I think Jimmy went about 20' further in practice after I cleaned the K&N air filter a few weeks ago for the first time. I told him I do it every season on mine, so once for a 2008 was kinda necessary. Thing looked like a furry stuffed animal when I started. She wasn't breathing too good.