I'm looking into replacing my cats to straight through pipes ,I've herd stories after de cat the car will smoke sometimes anyone know if there is any truth on this?

Also what do I do with the sensors the are screwed into the sides of the cats ?

If you have no cats the sensors can be removed, think they are cat temperature sensors

 

As for decats causing smoke, imo they don't, however they will highlight a problem if your turbo seals are already worn.

If you have no cats the sensors can be removed, think they are cat temperature sensors

 

As for decats causing smoke, imo they don't, however they will highlight a problem if your turbo seals are already worn.

 

Totally agree. It's not that decatting causes smoke it merely allows the problem to show. The relief of the back pressure that discourages oil from passing the worn turbo seals is lost, then smoke. Typically grey smoke at idle, higher revs cause it to disappear, it's not blue because it's uncombusted, just the evaporation from it.

 

It will decrease spool up times and change exhaust note. On an NA it can make things a little raspy and loud, the turbos will stop this though.

 

What you will likely have most fun with is removing the old turbo elbows which will be nicely rusted on.

Mmmmmmm might leave well alone then