Quote Originally Posted by SLow_POke
you will most defenately get a MIL if you hook up the O2.

the purpose of the second O2 is to check the condition of the CAT, if its doing its job. i had buddies just living it having with never getting a MIL . and why do you want a test pipe.?? just get a high flow cat, if its any deference
go with the test pipe and get a mil eliminator to get rid of the CEL. Pony Express makes a splice in mil eliminator for like $15. if you have a honda get the mazdaspeed protege one(it has the same wire diagram)