If you're supercharged or turbocharged it's likely you're approaching the limitation of your factory Mass Air Flow Sensor.  This sensor works by measuring the air traveling into your engine, allowing the engines computer to provide the necessary fuel. When you start to increase air consumption you reach the higher limits of the factory sensor, providing poor resolution for fueling accuracy. Or worse, you'll max out your sensor and as air increases, you'll lean out and cause potentially catastrophic engine failure.  Your factory MAF can support around 300whp, if that surpasses your goals, this is the ticket! We have proven MAF data for this setup and it's now a firm recommendation with any FI car we calibrate.