Right after putting in a full exhaust I'm getting consistently 20 mpg regardless of driving style...my driving style has remained consistent pre and post exhuast. Pulled the plugs today and each looks brand new, the a/f gauge reads between 14.2-15.7 at idle and cruising going down to around 12.5 at wot which seems normal to me. Anyone have a solution? Also replaced the upstream o2 sensor and no change and these are already heated in my year if im not mistaken. There has been a lot of these post with no real reason so im wondering why this happens from an exhaust

You might be able to ad some timing 2deg at a time till u see knock then back off 2deg. My last tank I got 31.7mpg. And I need to retune after my exhaust waiting on a new wideband cable.


see ya!

Do you think the problem is that the o2 sensor is located farther down on the pacesetter? If thats the case ill out the stock header back on and get a new downpipe made

If you have a heated sensor I don't think it's that big of a deal unless you have a serious leak someone near it. Is the connection to the downpipe knuckle style or a flex-pipe?


"In Oldskool we trust"

Its the ball socket joint that the pacesetter has...i have the bolts tightened down with a flex pipe. Would a leak at this joint take out 10 mpg? I used to get around 30 mpg on the highway before the exhuast

To be honest, you are probably getting worse mileage because you are getting on the car more, just to hear the exhaust. Not ripping on you, but it is what we all do, we want to hear our new purchase, and go through gas faster.

Honestly i am not getting on it more, if anything im easier on the throttle to try and save some gas. Guess its just my luck...when it was stock i got as much as 34 mpg (country roads) and as low as 15 mpg (air cond)

Go through all the header bolt/nuts. Make sure they are tight. You usually have to do this with any header at least a couple of times on a weekly basis till everything is settled in.

I usually will re-tighten them after the first heat cycle (heated to normal operating temperature, then cooled down), after a normal day of driving and finally at least one week after. It wouldn't hurt to check a month later also, to be on the safe side. After that they usually hold up for years afterwards.

Ya ive been keeping up with keeping them tight....just went out to see and they were all tight

After checking if those bolts where tight i said screw it and got a good sized 1/2in ratchet and tightened the bolts to the point to where they are probably torqued to 150 ft-lb and the blowing noise that i thought was just the noise through the header (because the pipes are thinner) almost went completely away and i just got 28 mpg on a short trip (5 gallons....40 city miles ~100 highway)...so if anyone else has had bad gas mileage after a header install dont torque to the 30 ftlb or whatever it was, just get a big ratchet and pull...just be careful not to go too much. So problem solved....glad it was that easy