Re: 25HP Kicker motor
It will work, the problem you may run into is having two motors of that size on the transom may possibly be too much weight, this will have the stern riding very low, that is if there's even enough room for both of them.
I used an 18hp kicker on a 16' that had a 90HP main motor and it handled it fine. I normally had a 6 on it, but it was in the shop. How well it works for you will depend on the hull design.
Something in the range of 6 to 9.9HP would be just right.
