The S2 has the same inlet diameter as stock (2.25”). Only things you will need to modify is relocation of the boost control solenoid. It’s a direct bolt in capable of 40 lbs/min of air flow. The benefit with the S2 over the S1 is added response and mid range from the larger A/R ratio of the compressor housing and an upgraded wastegate actuator. Peak power stays the same. This is what you get when you order an S2!