Quote Originally Posted by av8rps View Post
I fly a 4-1200 912ul on amphib floats with the IVO ULTRALIGHT 3 blade prop and agree the manifold pressure gauge isn't really needed. I also have a Lake Amibian with a constant speed prop, and there the mp guage is absolutely needed. But for some reason or other, the Rotax mp gauge doesn't move as much, so I pretty much never use it.

Rather, I listen to the engine to know if I am overloading or underloading it. I find 5,000 rpm to be a nice speed for my engine overall and find it runs smoothest there. But I believe every 912 has its "sweet spot", so just play around until you determine that with your Kitfox.

I think the 912 and the 4 were a match made in heaven...it's that good. I keep thinking I should replace my 80 hp 912ul with a 100 hp 912s, or maybe just Zipper kit my UL? But even though I'm on heavy amphib floats it does really good with that 80 hp 912 assisted by the IVO IFA. . I even have a spare 100 hp 912s laying around, but just don't know if it will make my plane that much better? So I haven't got real serious about changing it out.

Can anyone that changed their 912ul Model 4 to a 912uls comment on that? Maybe I'm not knowing what I'm missing?
the difference when I changed out mine was OMG.