Baffles, plugs or discs are a cheaper way to create back pressure for what is normally an UNTUNED exhaust system.
What RB Racing fails to mention, is that although race car exhaust may be straight through, the diameter, the number of bends, and the degree of those bends are all scientifically calculated to create a tuned exhaust, sans muffler.
Street vehicles are REQUIRED to have a muffler, by Federal and local laws.
"Backpressure" is a mechainical force that slows EXHAUST VELOCITY. By maintaining a 300 ft/min exhaust velocity, you maintain optimal power and torque via proper exhaust flow.
Lower that, ans the numbers lower with it. You may gain a small amount of HPs in the top end, but not torque.
Raise it, and the numbers lower again.
There are gimmicks on the market and there are things that are real, and people that know what works and what doesn't. HD uses 1.75" diameter exhaust tubing for a reason.
“When the going gets weird, the weird turn professional....” ~ Hunter S. Thompson~
R.I.P. Rubberdown. 1971-2012