[niarmsports]

after having the muffler and cat removed, my mileage gradually went down to around 8-9mpg. I had the turbo and tranny relearned and my mileage went way up to around 22-24mpg but then slowly got worse and is back down to 8-9. Seems to me like the computer is "rejecting" the exhaust mods.

 

[Rustin]

If thats the case scan it for codes and if you have a good scanner you could look at the graphs and see whats going on? Try to compare it to normal. Have you opened up your intake? Forgot any sensor?