Maybe someone can answer this but I am just wondering why nobody has tried doing an old trick with everyone running catless downpipes on here. Rather than eliminating the CEL with HPTuners why hasn't anyone tried the old method of installing an O2 bung, threading in a spark plug antifouler and threading the O2 sensor into that. That should keep the sensor from the majority of flow in the exhaust and keep from tripping the o2 sensor when not running a cat. Anyone tried this at all?

 

just get an o2 extender with a 90degree bend, worked for me...cheap on ebay

 

I tried it and it never truely went away. Light came on to much for my liking.

Plus since you wanna tune anyways why not. Even a stock pulleyed car can gain from a tune.