Stock Xr6T - Why Do You Need Mufflers On A Turbo?

[Jesse Williams]

Got half way through reading these replies and decided to skip the rest, so this may have already been covered.

If you change to a high-flow cat, then you will need a tune because the after-cat o2 sensor won't work properly and cause it to lean out, this requiring a tune.

Cat-back you won't need to do anything, other than try and refit the after-cat o2 sensor.

If you have a BF or BF mkII then the computer will relearn if you install a larger dump pipe.

Basically, of you change the cat, you require a tune.

[Never had any say Panda]

Yes.. Dump and Cat = Tune.. Catback is fine on a stock system.. But on a system where the catback may be providing a restriction (Already modded XR6T's) changing the catback may require a run on the dyno to check AFR's.

[Paulie2256]

Got half way through reading these replies and decided to skip the rest, so this may have already been covered.

If you change to a high-flow cat, then you will need a tune because the after-cat o2 sensor won't work properly and cause it to lean out, this requiring a tune.

Cat-back you won't need to do anything, other than try and refit the after-cat o2 sensor.

If you have a BF or BF mkII then the computer will relearn if you install a larger dump pipe.

Basically, of you change the cat, you require a tune.

The after cat o2 sensor does absolutely nothing apart from throw a code if your emissions don't meet a certain threshold. It does not do anything to the tune or change the way the car runs. The reason for retune after changing the cat is because the increased flow will cause overboost.

[Barra]

The after cat o2 sensor does absolutely nothing apart from throw a code if your emissions don't meet a certain threshold. It does not do anything to the tune or change the way the car runs. The reason for retune after changing the cat is because the increased flow will cause overboost.

Agree. Changed my cat not dump and no codes and will only overboost 3 psi max on a cold night if I push it. Getting AFR checked asap though.