The Grunt Box
The GruntBox is a simple solution to the dreaded "lean condition" that has plaugued MR2SC owners since its introduction. This condition occurs when running higher boost levels along with the stock ECU. The Gruntbox was designed to be inexpensive, easy to install, invisible to normal driving operation and requires no tuning whatsoever. The bottom line is, if you have added a pulley to your 4agze, you need a Gruntbox to correct your Air/Fuel ratios.