Catless DP's and emissions question

B6/7 S4/RS4
#1

Hey guys, just as the title reads. From what I have read, in chicago they only run the OBD test when it comes time for emission testing. If I gut the main cats but get the jhm tune, will I pass this OBD emissions test?

Thanks in advance

#2

I passed in Chicago and I’m full catless on the JHM tune. They don’t give a shit at the emissions places. Just some minimum wage guys who really don’t care if you’re spewing hydrocarbons

#3

Most places just require you to have your readiness tests pass and they don’t actually test out the pipe. I believe Chicago is one of those places.

#4

thanks guys!!! Exactly what I wanted to hear. I guess I have no choice but to get the tune and gut the pipes!

#5

should I just follow the pre cat gut thread when gutting my main cats? Im guessing its a pretty similar process there. Should I feel bad gutting the main cats on a 4 month old set of downpipes?? According to saki theyre expensive, more so than a set of oem totally gutted.

Thanks

#6

It would probably be easier and cheaper just to have Trexturk make you some.

#7

He is a member on here I believe can someone contact him and point him in the direction of this thread

#8

yeah don’t ever gut aftermarket downpipe cats. They’re worth more WITH cats on the used market, and you can just buy catless (or get TT to make you some) for way less.

No point in destroying the value of your aftermarket downpipes. Sell them, buy some OEMs and piggie them…or sell them, buy some 2.5" catless and scare the neighbour hood.

Personally if I were you I’d sell them and rock OEM downpipes with the precats gutted. There’s not a huge difference for a basic bolt on car from piggies to 2.5" catless.

I went from 13.21 @ 107.3 to 12.9 @ 107.8. As you can see the MPH barely changed…ET changed a lot though but that’s because the launch was aided by launch assist. The 13.21 time had a 1.92 60’ and the 12.99 had a 1.82. That’s a full tenth of the 0.22 ET gain right there…so again the gap isn’t that big between piggies + 2.5 catless.

Check this pull out…(me vs. the yellow car at 40 seconds)…we had the same modlists, but he had piggies vs my 2.5 catless downpipes. Barely any difference. Maybe 1/2 a car length? He snuck the jump a bit (bastard!) but still I didn’t get more than 1/2 a car back.

http://www.youtube.com/watch?v=7f7E-mNohP4

Here are the two timeslips of my best piggies vs. best catless

http://i375.photobucket.com/albums/oo193/sakimano/IMG_0348Cayuga13216at107Nov202010.jpg

vs

http://i375.photobucket.com/albums/oo193/sakimano/IMG_0028-1.jpg

#9

Even with the better 60ftnot reaction, Doh time don’t forget about the weather conditions. So there still is a performance benefit of a couple tenths and a couple mph.

If Dragtimes is correct the 13.21 was on a day where it was around 28 degrees.
The 12.9 was at around 64 degrees.

That is a pretty big temp jump.

Using the calculator which is just a rough estimate that would be a difference of a 12.93 @ 108.48 vs a 13.36 @ 106.27 w/ piggies. It’s not huge, but every little bit counts.

#10

it’d be interesting to see the gains between piggies and 2.5" catless downpipes on a car with the ported intake

#11

From what Ive seen your better off with the modded stockers. You can sell the miljunk and get a good chunk of your cash back. I would see if the textturk guy can make you some custom dps and just don’t go till you have your milltek Dp’s sold.

Then just take off the miltek dps after you got paid and swap them out then. That would be my suggestion

#12

  1. reaction time doesn’t count on ET

  2. conditions were better than that when I went 12.9…it was 54 degrees not 64. It was 48 degrees when I went 13.21, and the 13.21 day was into a headwind. Check your facts son! jk. Here’s a PM I sent the day I was at the strip running 13.21 (last november)…

[QUOTE=sakimano;15635]Well, I’m here again.

Track is right into the wind today. About 15 mph.

2 runs so far. Cooling down right now. There’s a Ford GT here and it may be the best looking car I’ve ever seen.

60’. 1.90
1/8. 8.59
Mph 82.7
1/4. 13.366
Mph 106.0

60’. 1.93
1/8. 8.67
Mph 82.47
1/4. 13.514
Mph 104.9

First launch was good…car spun, and just went. Still needs work.
[/quote]

#13

Thanks guys for all the input. Saki, great video, that navy avant rips man, wow. Sent my ecu in to jhm today for the tune, very excitedly awaiting its return. Looks like ill sell the downpipes instead of the gut idea/weld idea. Thanks for the input guys, Im now in the market for some oems i can gut or just some plain old 2.5" catless dp’s. Please holler if you guys hear anything for sale. Ill try to pm trexturk

#14

I updated the vid link…looks like I put the mobile version up before.

Funny, that Avant you saw walk the shit out of my car. Plenty fast car. Vast tuning/fuelling stage III B5 S4 with Frankenturbos, meth injection, ER intercoolers, full AWE exhaust. The real deal. Probably a 400+ whp/wtq car.

Now, here’s what happened that same weekend when we lined that B5 up against a B7 RS4 with a TVS1320 supercharger and a tune CountVohn wrote for the owner who was dissatisfied with the shitty APR tune the kit came with.

That red pair of dots about 8 car lengths away? Those are the RS4’s tail lights. This pull was from 1st to 5th…and like all the other pulls that day it wasn’t even remotely close.

http://audirevolution.net/addons/albums/images/695800780.jpg

#15

OMG

Can you post this video here? That is a certified ass whoopen

http://audirevolution.net/addons/albums/images/695800780.jpg

#16

lol sorry, I can’t. Maybe I’ll edit down an anonymous version for you guys. It’s pretty epic.

#17

Does anyone know how I can get in touch with trexturk?

Thanks

#18

Whats up man i thought i was registered, but i guess i wasnt lol
Hit me up and ill hook ya up man

#19

2nd time I’ve seen that screenshot, desperate to see that vid from Mexico lol.

In my mind, it’s piggies or headers if you’re starting from stock; piggies make sense either by gutting the precats or doing the JHM thing and sending yours back. If you don’t have any stockers to gut/send in then, catless DPs make more sense if you can get away with it in your jurisdiction. IIRC trexturks DP’s would probably be the best bang for buck.

saki’s comments re piggies vs catless DP’s are interesting, especially since he has direct before/after times. So it wasn’t just a hard sell on his old piggies :wink: They are great and I don’t have to worry about swapping DPs for emissions time - just make sure I’ve been driving around for a while.

NB Car 9506 FTMFW.

#20

oh yeah, you’ve got my old downpipes in your car. She lives on!

Those piggies flowed great. Best quarter mile MPH any all motor S4 has ever had with piggies. 107.3.