I have an 03 super glide carbed. Running Andrews 26 cams did plate and pump upgrade.. Adjustable push rods... When I had this done I was running hooker rebel longs... With bct baffles.. Small poops once in awhile... Being carbed I know it's the nature of the beast...! Lol
I just put on V&H bss.. With the bct's placed in the same screw holes as the standard baffles are mounted.. Now it backfires if I really get on it and let off.. Just thru exhaust not carb! Sorry I dont know the size at this time.. It was running a little rich befor so I dont thinks the problem is being to lean...
Any ideas on this? Thanks for your help!

 

My thinking is that with a free flowing exhaust,very little back pressure and a long duration cam,you're just burning off some fuel/air mixture that is being drawn into your pipes.

Probably need to lean her up a bit or introduce some more back pressure with a more restrictive baffle.