I don't think a tuner will help you if you already have a 2.5 bell type tuner on it. In my experience a tuner swap is a great way to wake up a motor, but only if it has a long restrictive tuner on it now. In example, putting a 2.5 HiPerf tuner on a 2.5 fishing motor. They came with the long tuner. Swapping a shorter bell tuner will pick up some top end hp, but you will really see a difference if you have a restricted exhaust passage in the block like on some of the old 150's and 175's. Grind open the exhaust passages to match a 2.4 BP exhaust adaptor gasket and bolt on a bell tuner and you're all set. I havent seen these "blockages" in the newer motors. Merc used exhaust restriction to "detune" motors for lower HP ratings. I also wouldn't recommend you read the tuner stuff on screamandfly that some guy named "raceman" posts. He is not a guru and has the tuner issue all wrong.