Some of the small Dolly muffs are not the easiest to mod. I can't recall if the 5105 is one of 'em. Assuming weight is an issue and why a 60cc saw was sought instead of a 70cc saw, then I still stick to the suggestion of modding the 5105. That said, 20cc jumps between saws works well for many. But I recently bought a MMWS 261v2. It made my slightly lighter 241 and somewhat heavier 7900 seem like extravagances. Ones I have hardly used since. I prefer instead to go from the 261 to the 395. It's quite a jump between cc classes and there is a small sweet spot between them the 7900 could fill, but probably not enough of one to keep it.