ive been given a asp .91m to my knowledge they are not great, on the website "just engines" it says they have 3.15 hp, max rpm 18,000 and practical rpm 2000 to 15000 was thinking of putting it in a 54 inch mono hull, it also has a tuned pipe, how do you think it will preform?

its also pretty light at 1000 grams

I hope you have lots of money. Nitro based fuels for that engine are going to be EXPENSIVE. Not only the "price" of the fuel, but also the amount it takes.

So I am running a ASP 91 marine in a JAE 90 rigger. Runs great and does not eat a lot of fuel. I feel that for the money the engine is a great deal and runs in the 60's with no problem with a pipe.