Ebay has several for the $30 range, actually they don't specifically say they are non-cat I'm just assuming. Is there any reason to stick with OEM on this?
Husqvarna 340 345 346XP 350 351 353 Muffler Gasket Bolts Aftermarket | eBay
Husqvarna 340 345 346XP 350 351 353 Muffler Gasket Bolts Aftermarket | eBay