cummins king

Hi
I'm planning on doing my car up a bit. I'm starting with the exahust. What I want to do is move the cats down about 6 inches and put in 2.5 inch dump valves. That way I can have the conveniance of stock exahust and have the sound and preformance of open headers, with the flick of a button.
My question is with moving the cats 6 inchs away from the sencers affect anything or trip any codes?

thanks
Joel

cummins king

bump?

white fish

2.7T?
if you gut the pre cats that will give you quicker spool up, cooler/happer turbos and will still pass e-tests

but you will need to relocate your 02's

look up "piggies"

cummins king

ya its the 2.7t, do you think it would make a difrence in preformance if i put the dumps after the cats

nothing77

I personally removed all my cats, but I dont have to pass any emissions tests. The problem with moving you cats is heat. Cats get extremely hot, Audi put heat shielding all around the current location of the cats, if you move the cats, the heat shielding wont be doing ****. I would gut the precats, Y in your dumps before the main cats, and relocate your secondary O2 sensor to after the main cat instead of before. It may be tight but it is absolutely possble, especially with the 6 speed tranny

cummins king

Thanks for info, i dont have a problem with the emissions either, its the popos that i have the problem with, if they saw me with no cats, they would ripe the plates off the car!

so im going to put the dumps in just before the cats, and move the sensors like you said.
But just one thing will moving the sensors affect the preformance of mess the computer up?

nothing77

Nope, not at all. The secondary O2 sensors are only there to measure cat efficiency, your primary O2's do all the fuel trim work.

K04-S4

CEL and intermittent DTC will trip after opening dumps if the dumps are before the cats and rear O2's. CEL may turn off eventually or if needed quicker, clear CEL with VAG after closing dumps.

cummins king

Okay, will it affect preformance, if those codes are tripped? and were will one get a VAC?

thx
joel

nothing77

it wont affect performance, the primary O2's will still be in the exhasut path, they are the sensors used to control fuel trims