Some are designed to trick the ECU into running lean or rich depending on the rating of the resister in relation to the oem signal range from the AFM sensor. So, on OBII vehicles, no. The ecu will learn around the resister and have you running back to stock within minutes.
On OBI, yes but dangerous. Its like an SAFC with only one setting with no variance and no way to tell what its set at. Try emailing the seller and ask what load resister is he using for the 7MGTE and youll never hear from him.
In theory, you could use a series of resisters and potentiometers on a vacume modulated variable control. One feed to the intake manifold and the other adapted to the RPM tach signal modulated in part by the throttle cable. Simple program base ROM board and a few days of tuning and programing in DOS you could make your own AFC but it would still be a tenth the speed and impossible totune and maintain.
In a nutshel, dont do it. Cut off your muffler, youd probably see the same gains and its not that loud at all and its free. No joke
