Regular Opti definitely doesn't have the balls of a Pro XS. Got a buddy that just replaced a 150 EFI with an Opti and I think the EFI had more power. Need to find what it takes to get the RPMs up in the power band like Pat says, or like you said, get a Pro XS or go to a 4 stroke. From what I've seen though Merc 4 stroke has more quirks than a SHO. Likes to run deeper with less pitch.