The OEM pipes do not fit because of the bracket and because of the chrome cover coverage. The OEM Valkyrie pipes are special. Engineers tried over a dozen configurations to get the perfect tone and pitch at both low and high RPMs, hence the different size silencers on the left and right. If you open up the muffler by drilling holes or reduce the back pressure, you will lose the glorious bottom end and midrange torque to gain maybe 2 hp at the seldom used tippy top RPM range. Leave a well designed system alone. It looks great with the OEM bags too. My sound has deepened with mileage and to me sounds great. This coming from a former HD owner that did pipes on both of my previous HD bikes. And yes without a tune, I lost bottom end and wound up with a headache after a 30 minute ride. Do you honestly think Honda which basically has an unlimited fund and team of engineers with years of experience made a mistake?