I stuffed my Encore ports a few times and compared. It didn't make the difference I thought it would. The bass is pretty tight ported or sealed at least in my set up. I have not tried filling the cavity more with polyfill, but that might be a test as well to reduce bass in conjunction with plugging the port. I thought I read you can do a front ported XLS, but it chuffs a little from the port when they are front ported.