I have a themoquad on my 440 and it runs great. Mileage and throttle response around town are very good. Tuned well, they offer great performance and driveability, tuned poorly and they'll make you want to throw it in the garbage can. I had to invest some time into getting mine tuned correctly, but once I got the choke and the secondaries setup properly, it was the next best thing to fuel injection. I drove my car to work every day spring-fall for 7 years with it setup like this.