When I learn something that might be important or at least interesting I like to pass it on. I had been aware for some time that I was gradually showing lower RPMs than I should have been. I was only showing around 4800rpm on takeoff and my cruise speed at 5000rpm was as much as 108mph, pretty dang good for a model 4/1200 with a 912ul. Too good I found out. I decided to temporarily wire up a Tiny Tach. It was worse than I thought. So I ordered a T-30 tach from Flight Data Systems. It verified that the Tiny Tach was right and my Rotax analog tach was junk. I now show 5200 at liftoff and 5450 at an 80mph climb out. I had bragged about cruising at 105+ at 5000rpm but I have to eat crow now. It just ain't so! 5000rpm gets me under 100. I have to run around 5400 to do 105+ now. So my old Rotax tach was at least 400rpm off. I guess I could add a little more pitch since I can exceed the 5800rpm redline at full throttle in level flight but I like the climb I get now. BTW this is my 2nd Rotax tach I've replaced over the years. The other one on a different plane. I think it was showing a higher rpm that the engine was actually turning. Anyway, the T-30 is a great tach, around $170 direct from Flight Data Systems and free shipping to boot. And great tech support too.