Yopu should be fine with a 225 and kicker. If your boat is rated for 230 and you repower with a 250, it will make it hard to insure. You can find places, but it limits you. Boat US will drop you if they catch you and many other big companies will not be liable. Since you are not running your kicker and engine at the same time, the kicker hp does not account for your 130. It does though get included in that max weight that is on that plate since it is part of your gear. Also what year is it? Pre SV2 hulls will be pushing it going to a four stroke of equal power. If you call Grady they can let you know what your boat can handle safely, their customer service is very good with that. 250 on a 208 might make the boat porpoise, which is unsafe, some year models have had issues at high speeds, not sure if it applies to yours. A 250, especially if heavier then what you have now will increase the chance of porpoising to occur. Best bet, call Grady.
