The shop installed a Magnaflow muffler. They claimed that they are "quieter" than Flowmasters. I originally requested a 50 series Flowmaster but decided to go ahead w/ their recommendation. After further research I noticed that Magnaflow mufflers (there is only one "type") are chamberless vs. the 50 series Flowmaster that I believe is 3-chambered. I'm by no means a muffler expert but I thought that a 3 chambered muffler would be quieter both externally/internally than a non-chambered muffler. The shop is willing to exchange the Magnaflow for a Flowmaster, I just want to make sure that I don't end up w/ a deafening interior.