If you really want a Kitfox to cruise fast, most important thing to do is to make sure you have as many lower false ribs in your wings as the Speedster / 1200 has per bay. The 1050 used one fewer per bay (as I recall), and consequently at higher speeds the pressure pushes the fabric upwards making the airfoil more like the original undercambered airfoil used on all earlier (and slower) Kitfoxes. That's why most 1200's fly faster than previous models whether a 32 or a 29 ft wing. At least that's my take on it.

Besides that, streamline everything you can and set the prop for a WOT max rpm straight and level of 5650 to 5800, make sure your flaperons and tail incidence allow the airplane to cruise flat, and you will be getting max performance out of a 912 powered Kitfox 4.

At least that's my take on things. I fly my 80 hp 912 Model 4-1200 on amphib floats with an IVO IFA, and I can easilly fly 115 mph even on floats. And there are still a lot of things I could do to "Clean it up".

I can appreciate your desire to have more than one Kitfox. And frankly, if I were only flying a Model 4 on wheels I would prefer a Speedster as it not only is faster and sportier, if done right they are really a beautiful airplane. Ramp appeal is off the charts...