I have a 2006 LT 3.9 and I plan on putting an exhaust cutout behind the o2 sensor and in front of the resonator. I've been looking over other exhaust threads and I see a lot of people talking about a 2.5 pipe but I can't determine it thats factory or if this section of pipe is smaller than 2.5 before everyone's modifications. I want to leave the complete exhaust system all stock with the exception of the cutout. What diameter is that section of pipe?

 

I read a thread that shows the 2000-2005 Montes are 2.25 but it doesn't say if that's the same for the 2006. I also tried looking for direct fit replacement catalytic converters but none of them specify the pipe diameter. The universal ones stating they work on the 2006 MC 3.9 have a diameter but do not say if they fit the factory pipe, or if the pipe has to be replaced with a larger diameter pipe to work.

 

The pipe has a 2.5" inlet diameter that tapers to a 1.88" outlet diameter. You would want a cutout for 2.5" pipe.

 

Awesome! Thanks Mike!