I have hear that without the CAT the O2 sensor won't work correctly because
of lack of back pressure. If you really want to bypass the CAT the best
solution is using an old CAT and partially gut it out then you will have a
bit of back pressure for the O2 sensor. Just hear say I didn't try it...

On Thu, Apr 16, 2015 at 3:58 PM, Jack Reynaert <jack007@comcast.net> wrote:

> Has anyone ran a 2.1L WBX with the CAT Bypass Pipe?
> http://www.busdepot.com/039251058
>
>
>
> I've referenced this blog on Samba.
> http://www.thesamba.com/vw/forum/viewtopic.php?t=389018
>
> Can't draw a clear conclusion, looking for input from direct experience.
>
>
>
> Are there any issues which should be considered "pros vs. cons" to running
> a
> 2.1l with a CAT By-pass pipe?
>
>
>
> I know that a Bung will need to be installed in the pipe to accommodate the
> O2 sensor, but will the O2 still send the correct signal to the ECU?
>
>
>
> What has been the experience of the elimination of back-pressure by running
> without a CAT help the HP and MPG?
>
>
>
> Note: the vehicle is not tested for emissions, so this is not an issue in
> our state. realize resale could be impacted (but will keep CAT on hand for
> that)
>
>
>
> Thanks!
>
>
>
> Jack
>