Personally I was blown away by the sound of the Cobra slip-on. Have heard drilled stock, Cobra swepts and V&H twin slash in person to compare.
Verses drilled, much lower/meaner but mine does decel pop frequently and it's noticeable verses the drilled stock popping
Verses V&H not nearly as loud but I find those a little too loud(guess I'm getting old because if it's too loud...)
Verses Cobra Swepts; toss up right now. Have to meet up with Patrice to see/hear again and refresh my aging mind. As for looks, yea the swepts have it beat there pretty easy but I'm "trying" to keep the mod cost down as best I can... Too many toys and projects at the moment to be spending extra cash on basically a 6 month distraction
As others have said get what you like. In the end you'll end up there anyway and if you compromise first you're looking at adding close to $250 to the final tab... Wait a little, meet up with some people in the area and if possible take a ride on their bike to really know. Waiting a little will save you cash and ensure that you get what you want.
BTW, personally I think even a full pipe install is within the wrenching ability of most everyone. Full pipes take 2 people but that's what beer and friends are for!!
Plus what better way to get one of your buddies hooked on the "Hobby"...