DynaTech makes a very good flowing muffler that really lowers your DB’s. Their also very compact 14’’ long and around 4-1/2’’ oval they sound awesome I’m putting a set on my boat. The Jegs part number for a 3’’ muffler is 329-76-014302. I’m just going to ceramic coat mine. The packing in them is stainless steel so I’m sure they will last awhile. They sound really good and deep. Their $80 each, Flow Master does make mufflers in stainless.