so my car was tuned with a cat in place. i am going to put in a testpipe. i am assuming i will not need a re-tune to run the test pipe??

a friend of mine has an s2000 and has the same situation..tuned for a cat putting in a testpipe..apparently his car will run lean now?? ithought it was the opposite and would run rich..

http://www.s2ki.com/forums/index.php...ic=528129&st=0

 

to get optimal power out of a test pipe you SHOULD get a tune. it is not necessary however. i think it may run the slightest bit richer

 

It will actually run a little leaner due to the increased flow. The buffer of safety left in your tune will determine the need for re-tune. Monitor knock if you have the means, but I think you will be fine.