New Member - 2009 Te 510 Muffler Issue

Hi all, new member to the forum, though I've been lurking a while - even some years back when, I had a '72 WR450 that I never got to finish restoring ...
Making amends with the recent purchase of an '09 TE 510, rebuilding as a Covid lockdown project (I'm in Sydney, Aus).
I know there's a bunch of posts regarding mufflers, including http://www.cafehusky.com/threads/sm510-catalytic-converter-removal.3299/, but mine has me mystified. I bought a repacking kit, not even thinking about cat converters (mine does not have one mid-pipe).
So ... frame number indicates it's an '09, but when I finally got the muffler apart (had to open both ends), out slides this big, ugly, sealed thing like a car muffler.
Am I correct in thinking this is actually an '08 muffler, with integral cat converter?
I don't want the bike to be much louder than stock - so, not too keen on the 'surgery' suggestions - but given that I now have four rivets rattling around in the front of this thing, is it worth cutting this open and persisting with it?
I'm lukewarm on buying a new aftermarket muffler, as the bike was bought cheaply, destined for hooning around a farm.

hard to say, but do you hear those rivets rattling in there, when bike is on, when i did not hear my

Do you have a pic of the outer can? The 08’ and 09’ pipes look completely different on the outside.

Hi again - thanks for your responses. I've been hacking away at it, will get organised and post some pics in due course.
Description in the meantime ... I cut open that sealed "inner" muffler, dead-easy job of just hacksawing the skin just inboard of the sealed ends. At the header end, I allowed some extra space as I'd read another post about the cat/other reason for extra thickness here - which turned out not to be the case.
I'd also figured on having to then cut horizontally along the skin to peel it open - but was surprised when this inner muffler just pulled open (i.e. end to end). Inside was ... just a muffler. No cat, just a full-length roll of mat (looks more like seagrass matting than fibreglass - and was in really good condition , which of course I discover after I've destroyed its housing), wrapped around a perforated metal pipe.
The trailing end, effectively an "inner" end cap, sits over the end of the perforated pipe and, being no longer attached by the inner-muffler's body, just slid off.
Regarding the rivets at the header end: frustratingly, they disappear into a weld-sealed chamber, between the front cap of the inner muffler and the flared-out header pipe. This little chamber does have matting inside, but I could hear the rivets rattling in there. Amazingly, I was able to manoeuvre and pull three of the four rivets back out of their original holes.
So ... I'm left with basically a conventional muffler. Have asked a mate who reassures me that the standard outer (alloy) body will have no issues with heat even with the inner skin now missing (would previously have have been about 3mm clearance between alloy external and stainless inner skin). With the "inner" end cap deleted, I just need to weld a 45mm length of s/s pipe (38mm inner dia) to the inside of the standard (outer) end cap, to bridge to the end of the perforated pipe. Down the track, I'll be able to repack it by drilling out the end cap and sliding new, rolled-up packing in, pretty much as normal.

Herewith, some pics. As mentioned, it's a 2009 TE 510, standard muffler. Going the el cheapo route, repacking and keeping it, as aftermarket options seem to be limited or NLA.
Part number (IMG 6071).
Component parts when cut open (IMG 6068).
Parts retained to modify/renew - awaiting only a 45mm length of s/s pipe to bridge end of perforated pipe and end cap (IMG 6070).
"Sealed compartment" at header end (IMG 6069) - I drilled a hole here to help with fishing out the rivets
Anyway, thought I'd just document this, in case someone was going to (needlessly) junk their standard muffler.