Don't forget to squeeze in the premeasured bottle of Whipple's own specific-viscosity lubricant. As visible in our lead shot, the company places a prominent red and white decal over the fill port to remind you. | 
This is the area beneath the rear seat cushion. There's no need to mess around under the car with the fuel tank; the fuel pump assembly will be swapped beneath the rubber cap on the driver side (arrow). | 
It resembles a simple cold-air kit more than a blower swap good for an additional 250-plus rwhp, doesn't it? Go ahead: Surprise your friends, humble your enemies. |
The factory twin-pump assembly is disconnected and lifted out to be replaced by the kit's higher-volume replacement. That said, the task is complicated somewhat by the fact that the hole in the floorpan doesn't line up well with the access port in the top of the fuel tank. Even so, it's one of the least messy pump swaps you'll ever undertake. Just be sure that the fuel level is low. | 
And here's the result: a happy, but near-frozen, Paul in a GT 500 convertible with frosted interior accents-and 674 rwhp. | 
Is this the world's most expensive snow thrower? Probably not, but with our Whipple twin-screw blower upgrade onboard, this may be the most fun you can have clearing a Michigan parking lot of a deep December snowfall. |
PHP boss-man Paul Svinicki flashes our subject '08 GT 500 ragtop with Whipple's outstanding calibration in preparation for some revealing dyno runs.
On the Dyno
We figured the twin-screw blower would make a difference, but we had no idea how much-or how soon. With a sleepy 2,000 rpm on the tach, the Whipple had managed to add more than 175 lb-ft to the Shelby's already impressive torque output. Talk about instantaneous throttle response. Also notice that the devilish torque peak of 666 lb-ft occurs about 500 rpm lower than the factory's maximum grunt number. OK, so it's torquey, but the Whipple also refuses to run out of breath. It hit 674 rwhp up at 6,300 revs, whereas the factory Roots starts nosing at 6,100, and all this is through a factory-stock exhaust system.
The truly power-mad will no doubt swap on a smaller pulley for even more boost (Whipple's W175 is said to be good for almost 25 psi) but will immediately lose emissions legality by doing so-and likely any hopes of preserving the GT 500's stock clutch and transmission.
Click here for the Shelby GT 500 Whipple Supercharger dyno chart