My car is a all stock daily driver - with historic tags , so no emission testing - it has some borla mufflers on it that sound like a quieter version of 2 chamber flows ( without the drone or popping ) the cats seem original ( 105k miles on car ) looks like 4 cats on there ( I heard the front 2 are actually “pre heaters “ for the real cats closer to mufflers - can the front 2 get removed without causing the ECU to go into safe mode and cause the car to not run good ? I am looking to drop the operating water temperature down a few degrees and have heard a free flowing exhaust helps engine run cooler - got a new 192 thermostat , new fan clutch and stock shroud - I imagine the exhaust will get a bit louder too , but that is ok .