Originally Posted by m3alabama
A clear sign of placebo is the "car revs more freely/faster" Rev speed is absolutely independant of any tuning changes that are made and is dependant on the gearing. A few hp here or there does not change the ease or speed a car reaches redline.
Also I don't get the 4500 rev limit until warm? Why do you need/want this over the stock parameters?
This is not true. If the car makes more horsepower and torque it will reach redline faster. If it produces more power, it will rev quicker. Take a car with the exact same gearing and everything else, such as a 328 and a 335. Does the 335 get to redline faster or rev more quickly while in gear? Definitely, it makes more power so it can achieve it faster.
The colder limit is so you don't over-rev while the engine is still warming up.