had quite a few rimfire mods to be honest on my hmr, for me the sak is certainly the best value for money but if you can/want to stretch your budget for something a bit nicer engineered and better sound reduction ( to my ears) and nicer looking , jeez how gay does that sound, then i have experience of the following
ase utra - quite heavy and a dull finish but very effective for noise suprresion , end of barrel mod
aetec - quite light and very nicely engineered and can add/remove baffles and to me looks the biz, however for noise supression on the HMR no better than the sak, but sooooo much nicer looking , its now on my ..22 annie 1417
wildcat reflex mod- quite a large, wide diameter mod , easily stripped and very good noise supression, this is on my hmr at the moment and highly recommended
DM80- as the wildcat to be honest and highly recommended only reason i sold it was it was part of the rifle package
LEI- this was on my stainless savage 93 hmr and is tiny, about 4-5" long and same diameter as a varmint barrel , sealed unit and to be honest it was amazing, not the quitest , but not far off , but very small, light and looked amazing
my choice now wouold be
1. LEI
2. Wildcat/DM80/ASE - choose which one you prefer
3. Aetec
4. Sak
hope this helps
cheers
craig