As far as Fox not liking people going with RPM claims, he also had an interesting idea about providing sample engines for magazine engine test columns. One of the engine testers for MAN mentioned this, in response to someone writing in about how he buys engines based on the reports in Model Magazines. He has never had any other engine reach the test results, even though he has often bought Fox engines that actually exceeded the reports' claims. The response was that, usually, the tester requests an engine from a manufacturer for testing. The manufacturer sends one or two, and requests that they be returned within a particular time frame. Indications are that the sample engines are hand-fitted prototypes built for reviews, not production engines. When he wrote to Fox for, IIRC, a sample .45, he received a pair of Fox Purchase Orders. The intent was for the reviewer to buy off-the-shelf engines from an LHS, so he could test exactly what the actual modeler would get. The reviewer for R/C Reports had similar comments.

I had the opportunity to tach an older Fox .45 BB of mine against a fairly new ST .45. The ST was only about 200 RPM faster than the 15 year old Fox, using APC 10-6 sport props and 10% fuel. The Fox has over 400 flights, and a couple vertical landings in dirt. It even survived hitting an oak stump dead center. It also has ben tached with a top end of 14500 and a sustainable idle of 1950 rpm.