I wanted to do a catless downpipe in prep for a stage 2 tune. It seems like its going to be a hassle though. When I need to get it inspected, it will fail right? Yeah. If I get it tuned, then the check engine light will go away but the actual emissions will be bad. If I replace it with stock for the inspection, the check engine light will probably come back on...right?


How much more restrictive is a catted downpipe than a catless? What are my options? I am looking at products on Way Motor Works, but that doesn't matter anyway.

 

Unless you go with a super low cell catted downpipe like a 100 cell you won't see as much gains as a catless. Where do you live? If you live in a state where emissions is done with OBDII you'll be fine on inspection once you get it tuned and the light goes away. Or you can buy a downpipe that is spaced out like one of MarioKart's and it won't throw a CEL. A state that does sniff tests will definitely fail.

Besides emissions there's also a lot more drone and noise with a catless downpipe so there's that. You may need to add a resonator in your exhaust somewhere to remove drone if you don't like it.

 

I live in Pennsylvania. I am not sure what they do here. I'll have to head to my local shop to find out. This helps thank you.

 

It seems it will be OBD or sniff test depending on shop/region. Find out what your guy does and if anyone else does OBD testing if he does sniff tests.

 

So as I understand it, if only the OBD test is done, I will be fine with a catless DP, is this correct? It is the "sniff" test that will get me into trouble.

 

Pretty much. And that's if you get a catless downpipe that is pre-spaced to not get a CEL or you get a tune that shuts the CEL off.

 

No, an OBDII test will fail with a catless downpipe. The tune tells the ECU not to look for the downstream O2, so the CEL will not come on, but when they test it it will fail for downstream O2 not ready and evap not ready (evap "trips" after 2 successful downstream O2 checks).

The real question is what are the standards in your state? My state only allows 1 emissions test not ready, and a catless DP will have 2. If your state allows 2, then you will be OK.

Eric

 

^He could just use Mario's DP (with correct spacing) and switch back to stock map when he goes in for OBD testing.

 

No, that will not work. I have Mario's catless DP (and I have no idea what you mean by "correct spacing"?) and when you switch to stock map you get a CEL almost immediately for the downstream O2. Tylewis, send me a PM if you'd like to discuss further what I've done, as I will not discuss it openly here.

Eric

 

Mario's new DP has the correct o2 bung spacing so it will not trigger the CEL on a stock tune.

 

I am facing the same issue and i live in NC. Does anyone know if we do sniff testing here? Also can i buy the exhaust and down pipe separate or is there a good kit that has both. Where can i a really high flow DP? Like 100 CEL

 

yes, you can buy the downpipe separately.
WMW has a 100 cel cat that'll fit.

 

Are you sure that it works? I tried spacing the downstream O2 using up to 3 O2 simulators (one at 90 degrees from the pipe), and I had zero success.

Eric