Ok, diverging from the topic post a little bit and to elaborate on what REX said.well... i hate to sound like a geek here but it is not like adding horsepower as with nitrous, bigger cams or turbo. technically it will not add any horsepower (to the engine) but it will free up hp to go to the wheels (whp) instead of trying to force gases out a restrictive system. freeing up hp and lightening the vehicle weight are excellent ways to boost performance out of a vehicle. lightweight wheels, crank pulleys, high flow air filters, cbe's and dp's are all good ways to increase whp without going into the engine internals. o.k. maybe i did sound like a big stickler ;D
i love the spt on my sedan! it does sound so mean as well.