Ok i have a show time that flew well with a 61FX, since i opted to use a pitts muffler, i made it a side winder, instead of using the stock mounting method at 45 degrees, I plan on putting a saito 91 using the same motor mount, sideways. Would the model fly any worse/better having it mounted sideways vs 45 degrees like the manual calls for?

Shouldn't make any difference! Enjoy it

he is correct, slap it on and enjoy

I prefer 90deg with 4-stroke engines. It will be fine, providing your take is in the right place for the carb location.

ok..... the carb is a little above the fuel line..maybe by a centimeter so that means ill have to richen the low end? i plan on running it on the ground tomoorw

I like my tanks center on the carb on my Saitos so they run the same inverted. Could be a challenge when one changes engines. Hope it all works out for you. I'm sure it will. The 91 is a good engine IMO.