John:
What Keith said brings back memories of watching the 4 rotor cars in the 80's, they were really fast. they used to run them here before the CART series and they had a distinctive exhaust note, and if I remember a bit quieter.
The biggest problem was the high heat generated in the exhaust system.
That six rotor has to be over 1200 hp.
Heat is a problem with all rotaries. The headers run several hundred degrees hotter than a piston engine. You should see the heat shielding just on a first gen RX7!