I bought the 4" megaphone because it was cheap for a well-known brand. It has glass packing but it uses a louvered core so it's more restrictive and stays quieter than most slip-ons without a decibel killer. Even after the packing is gone, it won't get way too loud. Had I known it used a louvered core, I would've bought something else.

The other problem was rust. The only parts on my Bolt that started showing signs of rust were the Hagons and the Bassani. I was going to have the Bassani ceramic coated and replace the core with perforated SS but figured I'd just cut my loses and bought a 22" ceramic Delkevic instead. Delkevic has other, cheaper uncoated SS options as well but like other short aftermarket slip-ons, their 16" is going to be louder. There's a trade off between muffler mass, exhaust flow and good looks.