.... options for the Spyder and HMF came up quite often as the best bang for the buck...... ..... 140 views and no rider knows the part number and only one response.
Could it be that some years back, when Spyders were just new on the scene, HMF was pretty much the only option that people could find, try, & knew worked; so in your searching here HMF presented as being the 'go to' muffler - but now days many of those 'first buyers/modifiers' have now moved on/stopped ryding & grown old as a result??? Did you check the date on those threads/posts?? Were any of them really all that recent?? :dontknow:
So it could be that back then, the people who were modifying their Spyders had a fairly limited range to choose from, so whatever was available featured highly on the Forum pages & scored lotsa recommendations. But these days, there are a whole bunch of 'newer' Spyder Ryders out there who are finding the A/mkt product range for Spyders has grown somewhat and there are now some other exhaust options; so HMF gets less of the Spyder/Market share, less presence on the Forum pages, and fewer of the current crop of Spyder Ryders run those exhausts on their machines - if any?!?!
Amongst the more recent offerings, RLS Exhausts comes to mind - they are a Supporting Sponsor here & as far as I can see from here in Oz, offer some pretty good products AND are pretty good in the Customer Service department too?! It's probably worth checking them out?! But there are others too....
Still, in almost all respects, for RS/RSS/ST's from 2013 & on, (with the 'bracketry proviso' I mentioned earlier

) they used much the same major engine components & exhaust set-up as the 2013 RT's did - so if you've got a 2014 RSS in need of a muffler then it will very likely use the same part number as that suitable for a 2013-2015 ST or possibly even a 2013 RT, but do check to make sure the brackets are compatible.... :thumbup:
Good Luck! :cheers: