Get a ZZP oversized tensioner pulley, that will make it so your belt wraps around the blower pulley more, and so it is tighter. Although everyone praises gatorbacks, I personally would not recommend them. They cost twice as much as any other belt, and have half the contact area because they are kind of grooved. Gatorbacks also stretch a LOT more so after only a few hundred miles it wil be loose and you will have to buy a new one, whereas with other belts that is not the case. With the GTP we ran Gatorbacks with no problems until we got the Intercooler. Once we got the intercooler the belt slipped like mad with the smaller pulley (2.7") if we went more than half throttle. We had an oversized tensioner pulley and could barely get the belt on when it was new. 1 week later it was way too loose and slipped like mad (as I described above) We decided we needed a smaller belt but no gatorbacks were available, so we decided to settle for just a regular Kelly Springfield. But, it seems to grip MUCH better, it cost half the price, and is available in a lot more sizes, and it doesn't stretch nearly as much as the gatorback. For half the price there is no reason to go gatorback. As I said, I have no problem with gatorbacks, they just cost too much, and aren't much better, if any better than other belts.
1990 Maroon Grand Prix STE McLaren 3.1 Intercooled Turbo, 14.695 @ 94.49 on 12psi before cam/heads/etc.
1990 Bright Red Grand Prix McLaren 3.1 Intercooled Turbo, 14.819 @ 92.72, 189whp
1999 Grand Prix GT 9.75:1|K&N|160 tstat|No Ubend/Cat/Res|UD Pulleys|Ported M90/TB/Heads|XPZ|2.55"|Pacesetters|Stage 2 I/C. 12.442 @ 112.78
2000 Blue Bonneville SSEi Supercharged Gutted Airbox|K&N|3.4"|1.9'*|WP Pulley|Custom DHP|180*stat|41932'*|No Cat. 14.681 @ 94.80
2002 Dark Cherry Grand Prix GTP Supercharged & Intercooled
12.084 @ 114.38 w/1.743 60', 315.6whp, Fastest Stock Cam M90 GTP!
NOW XP CAMMED, 340.6whp with XP, stock heads, Gen 3 M90, 11.984 @ 115.84 w/1.750 60'!
Most HP Stock Heads Gen 3 M90 GTP!
2004 Red Monte SS Supercharged K&N|3.4 Pulley|1.9'*|180*stat|41919 plugs|3" dp|No cat/ubend|DHP|Shift Kit. 14.2 @ 98
GOT BOOST??? Friends dont let friends drive stock!