This is what killed inboards for me. Since 2012, all inboards have been required by the EPA to have this super expensive cat converter exhaust with upstream and downstream O2 sensors, just like modern cars. Mercruiser, Volvo, PCM, Crusader etc. And, when it comes time to replace them, I know a friend who got an estimate of $4500 on a Merc V6. Not just that, but who would want a heat generator like a cat converter in the engine compartment of a fiberglass boat? I'm still astounded that the EPA got away with this making inboards both more expensive and more dangerous both at the same time. That's the main reason I'll never buy one of those, but the other outboard advantages just kind of sealed the deal for me.