gks4tip

Hello all,
New to the forum (Hope this post belongs here!)
I have been wondering about the performance of downpipes(say Milltek for my 2.7t s4 tip - yes they do make them!) as opposed simply piggying them - Im not really sure how this works though.

Oh and are the piggies road legal for Ontario Im not sure it counts as a simple repair/upgrade...

Comments, recommendations welcome

YYZ4.2A6

Seeing as though you are gutting the cats and removing a pair of oxygen sensors, I don't think anyone would call them "legal". I doubt the changes would ever get noticed though, except maybe for the visual part of an emissions test.

gks4tip

Hmm does that mean it wouldn't pass emission testing? Can the ecu work with two o2 sensors missing, i.e. would it not give some sort of error code all the time.. is that normal for piggied cars?

If the question seem too simple its cause I'm a bit of newbie, (in case I didn't say that b4) .. thNx YYZ4

Q-ball

I have to ask, downpipes are the headers?? what are the piggies? New to the car thing. I'm more into bikes and I want to get into cars as well, but need more knowledge and research.

just bough an 08' a4 avant about a month ago.

Black_RS4

I don't think it would show up on an emission test... as long as your audi is a quattro the inspection is just an idle test, as the test dyno cannot facilitate an all wheel drive vehicle

K04-S4

When done properly, piggie pipes do not eliminate any O2 sensors. They relocate the rear O2s to monitor the rear main cats instead of the forward and gutted pre-cats.

Aftermarket DP's are great but expensive. If you have the funds, consider these ultimate 2.7T Divorced Wastegate downpipes:

Tantrumwerks - Tantrum-Causing Mods for Your Audi/VW

Some good and relevant piggie pipe info at the bottom of this thread:

Fourtitude Forums: modified my exhaust go to youtube.com to hear it ...search for "2000 audi s4 no exhaust"

yuriperez

how much louder than stock are the aftermarket downpipes?

I have a 1.8T.

Would the engine pass emmissions w/ an aftermarket downpipe installed or no way?

Is the HP/Torque gain really that greatIs it worth the time and trouble?

If I install a downpipe with O2 sensor holes in the factory locations, will I get an error code from the ECU?

yuriperez

never mind

white fish

does anyone have piggies in the gta
you can pass emissions correct?

piggies = the 2.7 with gutted pre-cat and O2's relocated after main cats

K04-S4

I'm not in GTA but I did B5 S4 2.7T piggies myself as per VAST specs (aka Mike alias Mr Piggie)

You will pass emissions test in terms of no CEL. To be really safe, you may want to VAG scan for DTC's before testing. You will pass a basic sniff test as long as the exhaust and specifically rear cats are properly warmed up. With no metal substrate cats behind the Turbo's, your cold startup emissions may fail a test so avoid sniff testing cold exhaust.

When I APR Flip Switch between Stock and Perf code a few times, I get occasional stored DTCs that do not trigger CEL and if left alone they will self clear.

2 Faults Found:
16514 - Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit
P0130 - 35-10 - - - Intermittent
16534 - Oxygen (Lambda) Sensor B2 S1: Malfunction in Circuit
P0150 - 35-10 - - - Intermittent
Readiness: 0000 0000