From what I have been able to discern from input and posts the CMI/Mercury Marine HP525EFI header problem seems to be the biggest issue in 2003-2005 models and it is amplified on staggered twin installs and boats that have seen a lot of big water service and those receiving sub-par maintenance and service.
I am not sure on these dates but maybe some other OSO'ers can confirm?
In any event you obviously need a survey on the engines and a pressure test confirmation that the headers are not currently leaking and then maybe a once a year pre-season pressure test to confirm they are not leaking.

If you were out in the world looking for a
"NO THOUGHT" recreational performance vehicle, boats would obviously not be at the top of that list!

Old saying still prevails- "When in Doubt, Check it Out!"

Best Regards,
Ray @ Raylar

whats the difference between the sport tubes,,, built to cmi specs, and the genx???