I am seeing quite a bit of this here and many of the newer guys do not seem to be picking up on it. If your not satisfied or sure on the performance you get from your engine, then ask for help. Problem with this is you need to be aware of where the advice is coming from.
If your at 5000ft or similar, the numbers you get from a majority of the country can be near sea level and these numbers are way off and usually better performance. Thus leaving you thinking your engine is crap when that is the best you'll get.

I have a Jett .90L. With the prop Dub recommends, he gets in the mid 14,000rpm but he is in Texas. I am at 5000ft and mine are 2000rpm less but that is the best I will get up here. Lets go to Denver, were at the same altitude but the air is different and numbers can be better their.

You get a sea level response from Ohio asked by a guy in Ala&^%$bama. 2000%humidity, your going to have different numbers. Frankly I feel a majority of the problems is lack of proper tuning but thats my opinion. I have a F-20 and a Jett 50. I get around 115mph here. Guys in California a claiming 130-140 with the same set up.

Don't forget the DA, you can possibly add on a couple thousand more feet on any give hot 90 degree day.