Thought I would start a new thread as I have already searched and read heaps of threads on here where some of my questions have been answered but not all. I have also posted some questions in other threads with no response
. My questions relate mostly to the location of O2 sensors and mating an aftermarket exhaust to stock mufflers.
O2 Sensor & CAT
My understanding is that there is an O2 sensor pre-turbo and post cat. The ECU measures the effeciency pre and post and throws an error if not enough carbon emissions has been removed.
Q1. Do most aftermarket exhausts have a O2 bung in the mid-pipe post cat? I am specifically interested in XForce. I am just wondering if I bought a XForce TBE delete muffs, where would the O2 bung be?Apparently the CAT in dump is the best location. Either way I have noted that some good brands have this as either standard or option. XForce do a dump with what they call a pre-cat. Link to Xforce Dump with Pre-cat
Q2. Do you think this would be enough (without any other CAT) to stop the CEL from being thrown? as it only costs $24 more I can't imagine it does much to reduce emissions which makes you wonder why it is even an option. Or alternatively, this in combination with a 100 CAT should stop CEL? Q3. If I deleted the CAT post downpipe with an Xforce TBE, would I need a custom pipe (length of CAT) to fill the void?Fitment, Alignment and Stepping
I have heard that people fitting aftermarket TBE with stock mufflers can have alignment issues and require bending of mounts or heating with pole in muffler etc to fix.
Q4. Has anyone done/considered elongating the flange holes to allow for minor re-alignment/rotation prior to tightening?I understand that the factory muff inlet pipes are 1.8" and the XForce are 2.5". Although the pressure is lower at the rear of the car I still do not like the down size step as I believe it will cause turbulance and may impede optimal air flow.
Q5. Has anyone created a tapered spacer to smooth airflow or port matched the mufflers with a die grinder (assuming there is enough meat on the flanges without destroying the welds?Cheers in advance. Hoping keeping all this information together will benefit others also.
Cheers,
