There has been a lot of highly entertaining blather here, but the simple fact is that the 11-6 will work very well with the combo in question -- so will an 11-5 -- & so will a 12-4. An 11-4 will also work well, but at the cost of slightly accelerated engine wear relative to the other combos.

I have done many side-by-side comparisons of engines, & regardless of stated HP figures, a TT .46 Pro easily matches an OS .46 FX and often out powers it somewhat -- on the bench or in flight. It also can match the new OS .46 AX (which is barely more powerful than the FX, despit OS claims to the contrary). Additionally, the TT .46 Pro is actually more similar to the FX than the SF (having the same designer as both the OS engines) while being somewhat different in detail from either. It is also manufactured to ISO 9001 Standards, which the OS engines are not.

I fly OS, TT, MECOA & LEO engines -- all have the same design roots. The TT's are by far my favorite, in real world use.