CNT resonated testpipe review

Jordo!

Two questions:

1. I know it comes with an O2 extender, but it might not be long enough. Has anyone tried this trick:

Use TWO 18mm spark plug defoulers (you can get these at Autozone).

Drill one out with a 1/2 inch bit and leave the other one stock, screw in one defouler into the other and the O2 sensor on the end of that; install whole assembly into bung.

The way the ECU determines cat efficiency, and why this trick (usually) works: The ECU monitors the rate of change in narrow band O2 voltage between first (precat) and second (post cat).

If the second and first change at the same rate, that tells the ECU the cat isn't working and sets the code.

The extender creates enough of a delay in exhaust gas reacting with the sensor tip (if it works that is) to fool the ECU into thinking the voltage values are varying at different rates.

You can also fool the sensor electronically -- I can dig up the info on that if anyone is interested in trying it.


2. Any difference in prevalence of the P0420 between '09 and '10? Might be slightly different logic in the newer ECU's.