im looking to by a 1991 25hp johnson ob, my lake only allows a 20 hp. what is the difference between the 20 and 25 [other than the 5hp difference] the reason i ask is i had a 9.9 and made it into a 15 by adding bigger carb. at least that is what the shop told me. the 25 is camo painted with no stickers to show it is a 25 hp, any input would be appreciated thanks ken