i just bought a greddy header for my 98 gsr motor. my stock manifold has a o2 sensor in the bottom part of the manifold and in the cat. my car is a 96 civic with a obd2 to obd1 harness and a chipped p28. the header i bought dont have a o2 bung in it and someone told me that i dont need the o2 sensor in the header since i have the one in my cat. please help........