We purchased a 2002 Sunsation 288 and was told the horsepower was 425hp. We recently noticed that the sticker on the ECN box had a second sticker over the top of the original but (base) was crossed out and HO was hand written. What is the best method to determine if this motor was upgraded to HO ?
thanks

you can call Mercruiser helpline with the calibration number on the sticker on the ECU and they will tell you what it's calibrated for

not sure that the sticker will work as everything was hand written. When running side by side to another 496 running ours has more of a sucking air and a low to high thumping to it (sound wise). We are looking at putting this up for sale so price is a factor. Ive called the marina to have the computer put on the motor for the hours just not sure it will tell me about horse power.

Someone like Whipple who recalibrates them would need to look at the tune to tell for sure.

If it was a 496 mag that was converted to HO correctly, or an actual HO from the factory, the following should be found on the throttle plate:

The throttle body has a 75 mm (2.95 in) bore ( the 496/8.1 also has a 0.100" bypass hole for base model engines and a 0.200" bypass hole for HO [high output] models).

HO's have choppy idle over the mag
Also most HO's came with and x drive over standard bravo

It may have a Whipple tune if it's hand written

Ive called one our friends that is a motor head, hopefully he can he help. We have decided to hold off on the sale of this boat until we have a more definitive answer. Thank you everyone for your thoughts

My Whipple tuned PCM had its own Whipple sticker and left the 496HO sticker intact.

How do you guys attach to this site. I will put a video of the motor on this.