AlanC,
I put the Saito I.80 in because that is what I had. It fit well with very little cutting of the cowl. The stock muffler worked well too. I was surprised that even with the 1.80 I still ended up with the Rx pack and some lead on the engine mount. Adding the weight is no big deal, as it was more important getting the CG where it needed to be.
Happy Flying!
Loopman
