I have the L&L outside frame headers (460, f250, 6" lift, 4x4). Haven't finished the exhaust yet but it's basically a straight shot down the frame and dump in front of the rear tires. With a couple bends, I'm hoping to be able to tuck it up close the the bottom of the cab so it isn't as noticeable. Outside saves a bunch of hassle and expense on the exhaust. Also clears up the starter area on the pass side and clutch linkage, brake proportioning valve, fuel lines etc. on the drivers side. I have the Borgeson also and not interference issues. Did have some "fitting" to do at the front cab corner supports to let the headers clear.