Dlmob,
I found some engine weights for you:

Magnum XL-91RFS/22.4 ounces. Got this weight from Hobby People's site.

Thunder Tiger F-91S/26.2 ounces. Got this weight from AceHobby's site.

No doubt that the Saito 100 is the lightest. There is no weight savings with the Saito 91, may as well get the 100. The Magnum weight isn't bad if that weight includes the muffler. I think the OS 91 will weigh about the same as the Magnum. The TT is too heavy. No doubt that the Magnum is quite a bit cheaper than the Saitos. Hope this info helps you out a little if you haven't already made up your mind.


Wade