I've heard that these things are really only good for Auto trans cars, and in Manual cars they just make the engine knock really hard. As anyone here put one in their RX-7, and what are the results?

 

umm whomever told you this information is retarded. reprogammed ecu's run very well generally. most people generally use them on turbo cars to eliminate a fuel cut and to chagne the fuel and timing maps in the car so they can run more boost safely