I was wondering where do you guys recommend i have the bung welded in....before or after the cat? i've heard both ways but perferably before. Only reason I ask is that my comptech kit was running lean without a cat when i took it on the dyno and now I bought my own wideband and want to see if theres a difference with the cat on.


thanks
Mike

 

Before the cat for sure! After the cat will read leaner and incorrect (because the cat is doing it job by burning unburnt stuff off) mount it right before the cat.
Also be sure to mount the sensor at 11 o clock per the AEM etc instructions.

 

any idea then why the ctsc kit runs richer with a cat?

 

cat= bottleneck

therefore

o2 bung in the testpipe ftw