I know this has been discussed before Ive have read some of the post in regards to the walker and Donaldson mufflers. I want to get rid of the flowmaster on my dually. I want a deep exhaust note. I was wondering how loud the walker 21471 or the Donaldson m085171 was. I like loud but not obnoxious. these mufflers seem to be reasonable priced. If anyone has any experience with these your opinion is appreciated