So im looking at an evo8 with a buscher turbo back exhaust and and external o2 dump. any how it doesnt pass emissions in the state of utah. the car will come with the aftermarket exhaust installed but i will also be getting the stock, im planning on removing the o2 dump anyway i just need to know how to get the exhaust to pass and the o2 sensor to read. i was thinking of having someone flange the test pipe and a cat so i can interchange them when needed or just switch out the entire exhaust each time which will be a pain. any ideas?

also can i change out the dump tube for the stock o2 housing with out taking off the turbo?

 

Im also in utah and run a test pipe. I would suggest switching out the test pipe fot the cat each time the whole exhaust is a pain. I use the cell fix for the rear o2 sensor and have the tune set up so it passes with flying colors no matter what the mods are. Some people use the heat shield off the stock cat and weld it around the test pipe to trick whoever inspects it. Removing the exhaust manifold with the turbo attached worked the best for me to swap out o2 housings as the bolts can be stubborn. I would say do the heat shield trick unless you know the person inspecting it and can pursuade them not to look under the car.

 

If i switch out the test pipe with the cat will it pass for sure? and is the stock cat the same size as the test pipe or will i have to buy another cat? also with the cell fix o2 sensor do you still run your o2 dump or stock?

 

Which sensor are you talking about the one on o2 housing or the rear one after the cat/ test pipe?? The car should pass with a cat unless something is wrong but who knows the history of the car? The cell fix is for the rear sensor and tricks it to think there is a cat and keeps the check engine light from coming on. Both stock o2 and an o2 dump will have a bung for the front sensor and it should be reading unless disabled. Im not sure on the Buschur exhaust if the test pipe is the same size as stock cat but im sure you could find out with the search button.