I have a 17 TG and I believe after looking at the exhaust it has a header like the other 17 FLHs. It also has the a right side adapter/extension that reduces from (2.25" or 2.50"?) to a standard 1.75" muffler. Left side has a 1.75" to 1.75" adapter/extension from cross over pipe to muffler.

 

Bolted some Rush slip ons on my '17 today. No adapters needed.