Originally Posted by jsaredwings
so that pulley is just a tensioner/guide pulley, no purpose whatsoever? i know why you remove it just not sure why they put it there in the first place
That's just where they put it. It's an Idler pulley, meaning that it is there to direct the belt to the next pulley and is placed so it keeps the belt away from itself and other pulleys. The modded version gets you better, more reliable pulleys, and better wrap around the SC pulley to ensure no belt slippage in extreme WOT runs. Robs explanation on the NW site explains this much better than I can.