TUNERS

[O/B Dude]

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.

[You Te]

I had a stock tuner on a stock Merc 260 EFI a long while back. I was told by Gene (G-Froce) his tuner was good for about 15 HP. I bolted in on and nothing, RPM was the same, top speed the same, ET 1/4 mile the same.
One day about a year later I heard a rattle at the bottom of the tower housing, to my surprise is was the tuner.
Even with the tuner at the bottom of the tower housing the motor ran the same.
That is just my experience with the HP 260 motor, maybe on other motors it might help.
You Te

[yomama]

I recently purchased a used Stoker with a 2.5 EFI, 260 Merc.
I also heard a rattle in the tower housing.....bingo....G-Force tuner
banging around. Tubes cracked clean off the flange.....reinforcement
strap and all. Stocker is going back on !!!!