Well, i just had a look at the SSV, looked at their own dyno chart and compared it to the MREV2 + Spacer chart.

They're only showing it on the HR motor, best gains are made on that, more specifically, they're only showing it at peak RPM.

Most power and torque for your engine will come from the MREV2 and 5/16th spacer. More importantly, you'll get it low down as well. Personally, that's something i look for as it's power i can use everyday.