The muffler is built into the handle. It might be possible to cut out the "grille" over the exhaust, stuff it with some material, & then epoxy the grille back in. My main concern would be that it would most likely void the warranty.
That gun is also available in quiet form, but not Matco branded... the IR 2115QTiMax.
I thought the matco impacts looked a lot like the IR titanium max guns.