I'm buying 30' of one of these tomorrow night. I can get both for the same price. I've seen several Post about this, but very few considering both are the same price. The Royal Excelene is OFC, and I think rated for 350 amps up to 100'? (can't verify this) I've also read it is very flexible. The KLMX is CCA and (for sure) rated at 250 amps. The wire will be running from the front battery of an Expedition, to a HR500 battery in the back, powering a Sundown 1500d running into .5 ohm. (two Sundown z15's dual 2's). Any other advice would be greatly helpful also (box-ported or sealed, size, etc.) I want it loud, but sound quality is also important. I think I'm going with a sealed 5 cu. fl. box.