Hi Rob,
I can that the FP 20 with the BBTU does work "as advertised". Box stock so to speak (OS NVA and Venturi), 9-4 APC prop, 5%-10% nitro-1/2 and 1/2 oil blend. About 11,000 at launch (a "wet 2").
The FP 25 runs very similar, but is a little bit more touchy. For whatever reason, both do better if they are the latter ABN versoins, but I have also ran an iron/steel 20FP and it was very close.