We are on the same line of thought with regards to the servo setup

No pitts type mufflers for me as well. I got one for the 75AX intending to use on the problematic airplane with engine at 90deg but never used it. GP usually build a muffler tunnel into their ARFs. But in the Reactor Bipe they decided otherwise. It would be a good idea to try 135 deg installation but first I would have to test my 75 AX on another airplane for that.

The 91FS results in a much cleaner install with the muffler sticking out from below due to the in-cown extension I have already purchased. It also means that the cooling cutouts in the cowl can be oversized and on the underside so that there is the best cooling effect (India is a hot place in summer, you know). I think the engine decision will be decided primarily based on what is available at the time I start putting together the Bipe. That itself is atleast a season off from now and by then I will know how the first FS91SII performs in the Topstar (Flip-3D) so I am not too concerned for now. Am still undecided on the horn issue though, will decide at purchase time.

Anyway, thanks everyone for the help

Ameyam