I had a noisy can on my step through and was pulled over. Bike was impounded and I had to turn up next day with original exhaust and pay them to change it. Exhaust was confiscated although I managed to get it back under the table.
My other 2 bigger bikes have aftermarket cans on and I have not had a problem yet but I tend not to use either in town (Pattaya) and try to avoid known checkpoints.
I'm assuming the decibel killer is taking it down below obnoxious.
If you're not obnoxiously load & not out for attention, I wouldn't sweat it.
Last time (15 years ago) I got popped for that in Pattaya, was with drag pipes on a Harley. !,000 Baht, didn't impound the bike.
In our small village of Pak Nam Pran, many local kids ride around on obnoxiously loud motorbikes, and nobody seems to impound them. Can I get contacts of the guys who impounded yours? I'd like to invite them here to bring order to the little streets!