i went with the cycle shack MXL-330 slip ons for my '07 883XL. found them on e-bay, lightly used, and got a great deal... i had been searching the the cycle shack web site, b/c i wasn't sure what model to get. the site is a bit confusing unless you are familiar with their catalog, so i called them directly, and i found them to be very helpful. apparently, there are other cycle shack slip-ons for the sportster, but the folks at cycle shack steered me towards the 330's which in their view are quieter... well, the ones i got are PLENTY loud. very nice growl, and definitely gets that needed attention from drivers while on the road. would definitely recommend. straightforward install as well.
good luck...
ps - went with the "baloney" cuts, and like that look...
good luck...
ps - went with the "baloney" cuts, and like that look...