Going from the Foxbat to the Vixxen they claimed increase in cruise from 85-90 kts to 110-115 kts with the same wing and engine, just cleaning up the fuselage and drag, with a lot of research.
Surely where you are headed will always trump how far you can glide. No good gliding further to land in a forest. So wind influences your decision as to where you can get to, but that may be up- down- or cross- wind.
I flew out of Kyneton yesterday (Sunday) about 10.30am but most cloud was at 550ft AGL and I climbed through a large hole to the north heading for Bendigo but it just got worse so turned around and landed, put the plane away.
I know a caravan manufacturer ships Aussie steel to China where the chassis is assembled and shipped back to Aussie. They don't trust Chinese steel but the assembly and welding work is fine.