It would still void hull warranty. That Cougar is the original model “pre FTD”. Lighter and quicker according to most. Not that it matters, but has he exhausted all other options……..changing/experimenting with props, adjusting his present jackplate, etc? He probably has, but we dont know at this point.The XB was the “bomb diggity”. The XS doesnt have the same Ummph so to speak. Most see 75-81 with todays FTD/250 XS combo so hes not that far off.