Mention the name Geiger to a physicist and you're likely to hear about the man who discovered the atomic nucleus and the meter that bears his name. To automotive tuning fanatics, the name refers to the aftermarket firm that turns lethargic HUMMERs into tarmac-chomping beasts. But we're not so sure the two are that far removed.
Geiger's latest project is another riff on the relatively (and only by comparison) "small" H3, tinkering with the truck's reactor core to pump up its radioactivity. The stock H3 comes with a 3.7-liter inline-five producing a paltry 239 horsepower and 241 little torques, though it is available with a 5.3-liter V8 which still only manage 300hp and 320 lb-ft of twist. Along comes Geiger to fit a supercharger to said eight-cylinder, boosting output to 423