i have mustang gt 2002 5speed and with diablosports tuning and now i put long headers and xpipe and k&n fillter i have to make the tune agin. :eyes:

I wouldn't bother retuning it. Save your money for something else.

With the extra air flow you now have going in and out I would recommend a tune. Its not like you have to but it is always a good idea especially with the extra airflow.

Personally, I'd make a few pulls (dyno or street if you have a WB)
and check the A/F. I don't mess around when it comes to A/F.
Pay now or pay later IMO.

If it was tuned correctly, it should be self compensating.

To be safe, I would put it on a dyno. Some changes for the longtubes in "O2 sensor transport delay" might be needed.

Ryan

O2's can only self compensate so much. After that you could be in trouble

O2's are only part of the adaptive fuel control while at idle and part throttle. The EEC doesn't even look at them for WOT.

I would get it looked at just to make sure because mod motors do not like to be lean and a re-tune is cheaper than a motor. You have a lot more air going in and out and it would be better safe.

Yes a tune is needed. For some reason that LT's on a mod motor makes the a/f go rich. Something to do with the primary O2's being further from the exhaust port. I went from FMS shorties to BBK LT's and my a/f went from 13:1 to 12.6ish -Mark

I was running lean after I installed the LT's and x pipe and retuned it and no lean issues anymore.