so i drove my car tonight to pick up a friend and at first it drove fine, then i hard this wierd sound, like the engine but kinda louder, almost like a motorcycle or a lawnmower, i found it strange but the power was relatively the same so i keep driving, and i notice i drive for half an hour and my gas went down significantly. so i think in my head, loss of power and higher fuel consumption? its gotta be the cat? so im wondering is it more likely that its the cat or the fuel injection is putting too much fuel in the combustion chamber?

 

its a good indication. usually after running the car when these problem start happening pull off the road into a parking lot and look at the cat, if its glowing it usually will back up ur proof of real bad performance and mileage of the engine.

air pump still on the car? usually a stock cat doesnt live too long w/o seeing some fresh air.

do you have all stock exhaust at the moment as far as u can tell?

 

maybe an exhaust leak? I mean, if it is making a sound like the engine except louder, maybe your pipe rotted through, or broke.

I dont know about these cars, but on most cars if you were to cause decent exhaust leak (like opening a cutout) the gas milage would go way down, and so would low-end torque. The v8 cars probably wouldnt be affected nearly as much as a 6 though.

 

im not sure if i still have the air pump attached, i wouldnt know what it looks like. but i know the tail pipes and the headers are the only thing that were changed. the sound seems to come from the right corner, as if it were on the other side of the dash from the passenger side.