for those that like real data not guesses, I tested the same plane eng and prop combination on the same day with and without a supercharger. The higher I went the faster I went and the bigger the difference between normally aspirated and supercharged.at 5000 norm 24.5" 2300rpm true 205 at 12 gph. SC 27 " 2300 12.6 gph 208 true. At 15000 normal 16.4 " 2500 216 true at 12.5 gph SC 27"2500 245 true at 15.6 gph. All mixtures were 50 lop (im cheap)
Interestingly if you don't want to go over 30" at reno the speed of my plane was the same normally aspirated 25" as supercharged 30".The big difference is if you run the boost up or climb .
I removed the supercharger as the legacy at 215 true can get over 20 mpg. and thats fast enough for me . I can get up to 240 true normally aspirated but dont want the fuel burn . the supercharger can install in a day .the weight penalty is only a few pounds and doesn't show any big heat changes in the cowl. Unless you start building from scratch I dont think a turbocharger is even an option especially if you include an inter-cooler.