High Flow Cats

[MissSV6]

I have been told that if I get high flow cats installed that the engine lights may come on and if thats the case it will be $1000 for a tune up. Can someone shed some light on this for me? Is that right? and if so why would it cost so much for the tune?

[Surfwagon]

If your car is equipped with before and after cat O2's then yes you may need a tune but won't neccessarily mean $1000.
The mafless dyno tune on my LS2 only cost $850 and there is a lot more involved in changing over to mafless than just a straight tune to adjust for higer flowing cats.
Are you doing the rest of the exhaust at the same time or is that already done.
BTW it will still drive ok with the engine light on.
On LS# engines with 4 x O2's they usually turn off the rear O2's as they are only there to check that the O@'s are working as its the fronts that actually adjust the mixtures.

[MissSV6]

High the car already has a 2.5 single sports system and we are getting headers and high flow cats..it was the exhaust shop that quoted the $1000..so maybe we should shop around??

[colgf]

High the car already has a 2.5 single sports system and we are getting headers and high flow cats..it was the exhaust shop that quoted the $1000..so maybe we should shop around??

I had heard the same story, however I have just put "Hurricane" Extractors & 3" oulet into 100 cell High Flow Cats & & then full "Xforce" stainless 3" cat back dual exhaust thru to the dual 3" outets on my VZ Monaro LS1 & there's no light coming on at all ,& boy does it run & sound great too!!!!! I am extremely happy with the result. Maybe it depends on the system you use , some do some dont. Go ahead & do it , chances are it will be fine......