If the powerfilter for the X brings the RPMs up 150-200 RPM then what is bringing the RPMs back down in the kit to the 8000 where you're advertising your gains? If it's the pitch of the impeller, then what if you only buy the powerfilter? Would you be hitting the rev limiter?

The increase in rpm enables you to run a steeper pitched impeller producing more top speed. If you were to install the Power Filter only you would not only spin the prop when starting out (cavitation) you would hit the rev limiter before you even reached top speed. Also, your top speed wouldn't even come close to that achieved with Solas R-series prop.

That's what I thought and thanks for the answer. If you can answer this, will the Stage II for the X models require any replacement or removal of Stage I parts? The reason I ask is that since this model seems very dependent on all Stage parts to be used together then I can see a potential for the increasing of something in a Stage II kit as requiring modifying something that's already been modified (or paid for)...does that make sense? I don't want to spend money twice.

Thanks!

Sure it make sense! The prop will need to be changed. Other than that all the other parts will be in addition to the Stage I parts.

When setting up our Stage Kits we make every effort to "add" to each kit to keep the cost down.