Exhaust Recommendation

[JFFerner]

I read your note here about chip calibration modification when converting to a free flowing exhaust system. What happens if cut outs are used, assuming one usually drives with the cut outs closed, opening them only occasionally?

[TX '90 ZR1]

Paul,
Clear as mud??? Yes, but surprisingly I understand what you are saying!
Good point about the tune.
Also, the previous post by JFFerner raises a good question. Anybody have an answer?

[Mr Blue]

IF my understanding is correct, calibration should be for the most free flowing exhaust condition. This is so that you don't run overly lean in WOT and fry something. If you have cut-outs, you might run a little rich in WOT with them closed,but that's safe. In part throttle, as I understand it, fuel is governed by O2 sensor and the ECM. Someone correct me if I am wrong.

[Paul Workman]

Marc or Dominic or Pete can better answer. However, IIRC when I asked Marc about it, he said he tuned it with the mufflers removed - which would make sense if tuning for peak performance (i.e., mufflers off during the race or high performance demand). Also, to avoid LEAN conditon at WOT.