So with a 2100 muffler no mod is needed.
I found a 2100 muffler with the top exhaust port and the imbossed square for the lower exhaust grill type port. I have the screen for the lower port but I need to fab the four screw slotted grill frame. I wouldn’t be adding much to the flow of the exhaust. Just a tad more flow.
This is the jungle muffler:
https://www.arboristsite.com/community/media/jungle-muffler.893/
NOS in package on ebay was around $45, but did not have the spark screen
This series all came with the outer slotted grill baffle. Most came with either or both, the spark screen and an internal round can baffle. All 3 pieces were held by the 4 outer screws.
IMO just the slotted grill alone is all you need and want.
My 298XP has the top/side exit muffler. It's OK, but I like the jungle one, as is, much better
https://www.arboristsite.com/community/media/albums/husqvarna-4.80/
If you can follow my data...
HUSQVARNA 56mmx40mm saws
Rev# by cronological sequence
1100CD-73-03 #
1100CD-75-08 #
1100CD-76-11 #
2100CD-76-12 @
2100CD-78-01 @
2100CD-78-09 @
2100CD-79-06 @
2100CD-79-12 @
2100-82-11 %
2100-83-11 %
2100-84-04 %
2100-85-8 %
298XP-86-4 *
298XP-87-1 *
2101-87-4 &
298XP-87-6 *
2101-89-02 &
2101-90-6 &
Mufflers
501 29 47-01 #
501 48 61-01 #@% screen-baffle-cover
501 57 29-01 #@% side exit-screen
501 59 52-01 jungle early baffle-cover
503 17 28-01 Jungle late cover 85-08 + &
503 41 69-01 * screen
503 41 69-02 * open
503 53 06-01 & screen baffle cover *baffle cover
503 53 06-02FF *& screen