question me and my friends were arguing about is i got rid of my cat on my 08 si it would affect my a/f and i would have to get re tuned since the sensors would be positioned differently on the test pipe because i will have a bung welded for the primary and secondary. note: im turbo so if it effect my a/f i would needa get retune but i told him that it wouldnt affect anything any have input on this? also should i just eliminate the seondary o2 or should i have a bung welded for it since i dont think it will effect much correct? some one help me im a noob to this kinda of stuff.

 

your car will run a little more lean. i dont know if its enough of a difference to cause you to need a tune. since youre turbo, dont you have a wideband?.

you should not remove the secondary o2 sensor. get the defouler and have it installed. you wouldnt be able to get rid of the CEL if you got rid of the secondary o2 sensor completely.

 

If you have a flashpro you can just disable the secondary o2 sensor.