Thanks for the input/comments. The weight difference between the OS91 and the OS46 is 8 ounces. Overall weight difference might be about 12 ounces (a slightly smaller pipe and a bit less fuel). From what I have read about the OS46 VXDF, it is quite a good engine .... and much improved over the 46 that OS had a few years ago.

As far as putting a turbine in this Hawk .... on the box it says 'Not suitable for turbine installations'. Thanks. Bob