Ok i have a 99 360, has a cat but its punched out for a 4 inch straight exhaust it dosnt happen very ofter but i throw the check engine light, knew i would by doing this and we dont have emissions test where i live so,
could i use an o2 sim or a non fouler???. would that stop the light and make my truck run the way it should.

 

Get two non-foulers (18mm) and drill one out. Install non-drilled into bung in exhaust. Install drilled one. Install O2 sensor. Shiuld be good.

Theres a DIY in the faq/diy section for more specific instructions.

 

Hey thanks alot did it and so far so good went pretty smooth.