[jaybirn]

I have been thinking about this issue quite a bit recently and I have a theory regarding the use of defoulers and Vibrant headers with high-flow cats. From the information I have seen, CEL problems are hit or miss for people that have this header. What this leads me to believe is that the HFC brings the emission levels of the vehicle to a point that is right on the border of throwing a CEL, making it a coin toss as to whether or not a code will be thrown. Given that a defouler is meant to bring the oxygen sensor away from the stream of exhaust, it makes sense to me that in a HFC installation (more specifically with the Vibrant header), that ultimately less deflection of exhaust gases is needed than a catless setup.

So here's my theory for a DIY defouler. Rather than using two of the "Help!" defoulers stacked on each other (causing clearance issues), one defouler that has been drilled out can be used. I haven't seen how long the tip of the oxygen snsor is, but my thought is that the end of the tip would be exposed to the direct stream of exhaust while most of the tip (with 90% of metering capability) would be deflected. It wouldn't make a huge difference, but it might make enough of one for people that are running HFC's and don't want to fork out the money for an angled defouler.

Has anybody thought of or tried this? Any thoughts?