I've now used Mane Event bags for years - 1 pair for standard GS cases with exhaust cut-out and another set for use with a full size lh case when using a stubby exhaust (ie bags for an RT etc) - great bags
There a set of Mane Event bags in the "For Sale" section just now - which look like new - there for full size cases but you could still use them in GS caseswww.ukgser.com/forums/showthread.php?364595-Mane-Event-Inner-Bags-BMW-02-Oilhead-1100-1150
I have a set of the Kathy bags and a set of Bestem USA bags. I like the Bestem bags as they are more rigid and keep their shape even when empty.
The Kathy bags are easier to use especially the smaller left side pannier. Once they are packed they WILL fit into the panniers. The left bag have a zip to expand if you have the larger pannier.
Quality on both are excellent.