I've only had the coach out three times and really haven't listened enough to it yet to see if it's any louder. I did look at the plumbing and lifted the end of the exhaust, making it tighter to the coach. I also like to reverse the U bolts so the threaded ends don't hang down.
The way the Oasis exhaust is currently plumbed, is different than my previous coach. They dropped the Oasis exhaust pipe through the bottom of the bay floor, right next to a 3" wide frame rail. Consequently, shortening the exhaust pipe coming out the floor and installing a muffler may be tough. The frame rail is creating a fitment issue.
Don & Mary
2019 Newmar Dutch Star 4018
2019 Ford Raptor