I have read the previous bit on this but wanted to know for sure what needs to be done. I have a 98 9.9 merc. I have just installed boyesen reeds and need to know what else to change to make it a 15. DO I need just the jet or a new carb? Is there any difference in the exhaust side? Also what prop(larger? more pitch?) should I use on my 12' Harbourcraft fishing boat? I am looking for a little more get-up and go and even more top end. Thanks in advance T