I haven't seen dyno #s lately, but from what I have read over the last two years, removing the cat does little to increase flow or add performance. What it does do is decrease heat and maybe improve sound. A lot depends on what else you have done to the bike.
Right now, my '17 RGS only has V&H HOs, stock headers with cat, stock air, and a warranty.
Runs and sounds great. Head temp a little elevated, not much, can't remember the #s. No backfires, popping, any of that.
At two years, gonna add a PV to richen up the fuel/air mix. May and add either a K&N or a Big Sucker, someday. Stock AF flows plenty of air for what I need.
John, Medina, TN - 2003 Honda ST1300 ABS, 2011 Kawasaki KLR 650, 2012 Ducati Monster 1100 EVO
2017 HD Road Glide Special