Always use a factory belt. The primer on Bay 13 is pretty much right out of the book and just as they teach it in Volvo school with the two additions of the bungee cord and the needle nose vice grips. Both of which work very well. The only thing that I do different is that I go ahead and pull the crank dampner out of the way. It is only one BIG nut and four 8mm bolts. You can go ahead and lever it out of the way with a big screw driver/pry bar. Once it is out of your way you won't have the hassle of trying to route the T/belt underneath it and it makes it pretty much a straight shot to get to the tensioner bolts. I use a 3/8" drive 12mm impact swivel socket to get on the tensioner and it comes right out. With it out of the way you will find that the tensioner can be removed and installed from the bottom without a problem and you can visually inspect the bottom of the crank gear to make sure that the belt teeth are aligned properly. If everything is aligned you will find that the tensioner will sit right back where it came from, if you have a place where the belt is not engaged (like the bottomof the crank gear) you will find that you have to fight to get that tensioner in. DO NOT FIGHT IT, re-check your intstallation and all timing marks. Lastly make sure you put the little tin sheild back onto the front of the oil pump BEFORE you put the serpentine belt on, you can do it the other way it is just easier if you do one before the other. Have fun and good luck.