Got to run one the other day, 2.8L inline 4 with dual overhead cam with variable cam timing 480 lbs Didn't have as much low end grunt as the the big block sho's do but really ran well on top end my opinion better than opti 150pro xs or hpdi 150. They also had a 200hp version without vmax graphics that was also very strong and light weight.
I much prefer the yamaha over the merc 150. After running both the yamaha is a true bred bass motor as the merc don't have the low end nor the top end the yamaha does. And im a believer in the yamaha technology most all is derived from its big bore brother.