Are throttle body spacers effective

Answer 1

No. Not in today's cars. All new cars are MFI, multi point fuel injection. These spacers may have some effect in older cars which utuilize TBI, throttle body injection, where the fuel is mixed before the throttle body. Simply put, it has been documented and proven that these spacers have little to no effect on new engines. You would be lucky to see a 2hp improvement. If horsepower could be so easily manipulated by the shape or size of the throttle body, the manufacturer would have made it into their design.