Have you listened to your XL with someone else firing it?
I find mine is so quiet, that big muffler does exactly what it's supposed to, that I hear every other little squeak rattle & roll
I'm not saying it sounds twangy at all, & I haven't had it apart yet, no need, after some 3000+ pellets but when my son's fire it, with me alongside, it's a very solid sounding little rifle.