Hi all.
I used the Gronk mod from another forum to modify the mufflers. 1 3/4 " hole saw ,drilled the end and pulled out the baffles. Used a drill press and with a 1/4 " bit I enlarged the baffle holes as well as adding two more rows at the outlet end of the baffle. Cleaned the baffle with a small threaded rod to get rid of any fragments still hanging on. Then I took them to a muffler shop and had them mig weld the baffles in once again. (taking care to use a wet rag to keep the muffler ends cool,no blueing. total cost about $40.00 plus breakfast. You can here the sound on youtube. Just click on Harley Sportster with Gronk mod. It gives me a nice deep rumble without being too loud. At sixty years old I prefer the deeper rumble. The mod itself took me about 1 1/2 hrs. By the way Don't knock the inner cap out of the baffles . It's all stock except for the resized holes, and looks completely stock on the motorcycle. I like the look of the stock mufflers.
Best Regards!