2003 Mercury 2.5 xr6 porting

[Kdybalski]

I have a 2003 2.5 150 xr6 that I want to get extra performance out of and thinking about changing the port timing while the block is apart and putting a better timer on it while I am in there. It has super low hours, but had a problem with one piston, thus the tear down. This motor does have the compression relief built into the cylinder. Some say no go on any mods, but others say it does not make much difference and will respond to port work? Any suggestions!! Btw, motor is going on a somewhat light bass boat and want to get over 200 hp to push lager prop. Some say the motor stock is around 168 to 170 hp now. It has the bigger carbs on it now. Any other mods suggested. If you say tuner, which one. What’s best bang for buck.