I think in the case of stock pipes. The mufflers should provide the needed back pressure. In my case with the swept pipes. I am going to pull the baffles out and see what they look like before I decide to gut the cats. If I have to add a fuel controler then I'll do that. I might just go with thunder baffles.
I am frankly upset that I spent a grand for vic pipes just to find out they are worse the stock.
99 Kawasaki Vulcan 800 (sold)
2012 Vegas (traded)
2013 Cross Country Tour
Victory Tri-Ovals, Reverse Kit, Lloydz air filter, Lloydz quarter turn throttle ring, PCV, Lloydz Touring cams, HMD Bars, DGD keyless ignition, Rockford Fosgate Amp, klockworks windshield. 119hp 123lbs torque.