Unmuffled rotaries are the loudest motors you can get. For a 1300cc you'd my old friends was unbeliable when he had the headers off. They are the only cars that require mufflers in most racing (but not drag). BTW, how do you know that is a 4 rotor. Those are VERY rare engines. Usually they just race the regular RX7 engines and replace the bearings and seals in drag mode. You can get about 600 out of a 13B with sequential turbos and a blower.
