sab3r,
NHRA has basically, divisions. The professionals, which includes classes of Pro Stock, Top Fuel Dragsters, Top Fuel Funny Cars, and Pro Stock Motorcycle. Then there is the sportsman division, which includes classes of stock eliminator, super stock eliminator, super street, super gas, super comp, and comp eliminator, Alcohol Funny car, Alcohol dragster and top sportsman. The cars only race against the cars within their respective classes. The only classes where roots type superchargers are allowed are Top Fuel dragster, top fuel funny car and the sportsman classes of top alcohol dragster and top alcohol funny car. Believe me, I drag raced at NHRA events and they try to keep the playing field as level as possible; Going as far as a mandatory inspection and engine tear down if they think you are up to some trickery. They place the most scrutiny is placed is amongst the stock eliminator and super stock classes. Lot's of trickery going on in those classes, as the engine and chassis specifications are more regulated.