I'm running a D1 - spearco intercooler 7.62 to 3.40" pulley 12 rib setup. Belt alignment is critical. Had to engineer/machine a crank spacer to get good belt alignment. Also, I noted that the ATI tensioner internal spring can hang up (coil types inside). I dissected the tensioner and allowed for free movement by removing some metal for free travel. Also, made a pivot arm stop to limit tight side - loose side tension. I think that helped alot. I don't have any perceived problems now. (97 - 383 LT1)