Well, my gas mileage blows. My speedometer hasn't worked in about a year but it works now so I checked my gas mileage last night and got 10mpg. Thats with around town and highway driving. I guess i'll give the car a code test and see if any sensors come up. I kinda think the problem is since i'm running a 24lb pro m 80mm mass air with 30lb injectors and a pro m remote optimizer that the 'tune' might be off. Im thinking of buying a 30lb mass air. I remember my car used to get around 16mpg with mixed driving and beating on it. My O2 sesnors are about 4 years old. One quick thing about the O2 sensors, does it matter which harness they get plugged into? Is there a left and a right for them or it doesnt matter?