I am putting a 5.7 V-8 in place of a 4.3 V-6 (175 HP rated by Merc)in my baja. I was wondering what the advantages and disadvantages of just putting a different prop on the boat VS regearing the drive to 1.5 : 1(Current ratio is 1.84:1.)and putting a different prop on were? I am running a 14.25 by 21 SS prop now. Either way I need to do something or I will bouce off the rev limiter. I am hopping for about 300 HP when finished rebuilding the 5.7. What kind of speed should I expect? The boat is an Islander 180 and it runs at 49.5mphGPS at 4900 rpm right now.