When I got Fat Robert he he had Thunder Header. A great sounding pipe, but just too loud. Yesterday, the Thunder Header came off and and a set of Vance and Hines Big Radius 2 into 1′s went on. Not as quiet as stock, but much quieter, say by half. Next, to complete the project, a Power Commander and dyno tuning.

My pipes! What happened to my pipes?

That's better.

FXDF Dyna Fat Bob with Vance and Hines Big Radius 2 into 1

Thanks to Nathan for helping with the installation which was not too difficult, but had a few hitches that one person alone would have had a hell of a time resolving.