The 90 HO is a V-4 and same weight as the 115. The regular 90 is an I-3, so yes, I think it's about 50 lbs lighter. Max HP may be about the same but due to 33% more displacement, I'm sure the V-4 has a BUNCH more mid range torque! The HO models seem to be BRP's way of allowing you to mount a bigger "hot rod" motor on smaller boats without exceeding the Max HP rating and triggering higher insurance rates! Detroit did similar sandbagging late in the muscle car era, just before smog rules killed the hot engines!