I had the same experiance with the 4.5, I have one in my scte and it's a beast, mild in the sc10. My truck has way more drag then any shaft drive I have. I swear its the diff cases or that flange they leave on the idler and diff rub if the cases are to tight. The belt drive is smooth turning with no diffs installed. I might grind the flanges off to see what it does. I tried flipping the gears and it still does it. I'll figure it out soon. I'm waisting power with all that drag.