Currently I have a ZZP catted downpipe on my car and I have been unable to get it through emissions in Maryland. I have tried several defoulers but they have not done the trick. I have seen a few posts elsewhere that the Hahn downpipe does not throw cel codes. Does anyone have any experience with Hahn? Thanks for the help.

 

I have the turboxs highflow cat dp never gave me a code but my o2 sensor was never ready but since in texas I can have 1 without being ready I would still pass

 

Turn second 02 off in hptuners

 

I passed va emissions with a stock gutted cat Hahn catback and other small mods on stock turbo

 

I pass it with all the mods I have on the car

 

It was turned off but in Maryland their system can tell if the monitors are not ready and they will not pass you.

 

So you need all the monitors ready? You wont pass with 1 not ready?