No cats need be harmed in the increasing of one's horsepower (how did so many animals make it into this tip?). This means that you straighten the pipes from the catalyst in the exhaust tubing to the back of the car, at the bumper. "This will loosen up the entire system," said Jeff Zurschmeide, author of "The New Mini Performance Handbook." "It pushes the exhaust gases out easier." Getting those gases out ASAP means more room for more air and fuel, and more air and fuel means more power. Zurschmeide notes that "new catalysts are less restrictive than they used to be, and they're designed to work with the engine. They're not such a bar to performance anymore." If your car is, ahem, vintage, you might want to check out tip number 3.