Car I own: 2010 Cobalt SS with RPD

I am from the SRT4 world so this is a bit different so sorry for the stupid questions...

1. Since I live in Texas I am looking for a better flowing downpipe but with a cat due to emissions...is there one that everyone agrees is the best catted downpipe? I read zzp allot...

2. How much HP am I giving up going free flowing catted downpipe versus catless on these cars? Is it worth adding the catted downpipe or should I just keep the OEM...

3. I am going to buy the TurboXS FL cat back exhaust .... how is the fitment with TurboXS and ZZP or should I go with the TurboXS catted downpipe to avoid any fitment issues?

4. I have the RPD ( performance display ) and since it already has a wide band readout ..I am concerned that if I change out my down pipe it will no longer read correctly...is the wideband on our cars positioned before the cat on the downpipe? Will changing the OEM down pipe in any way compromise the readout on the RPD?

5. To avoid a CEL do I need defouler on the catted downpipe...just in case? this http://www.modernperformance.com/pro...aust_universal

 

You can run a catless dp in texas and pass test no sniffer its an obd emmisions test just get catless with angled o2 bung so no codes get thrown. A high flow catted dp will flow much better than stockbut not as good as catless and rpd will work with any of these setups

 

Still leaning towards the catted as my SRT4 had a catless and it stunk in the cabin.....I would like to avoid that this time.

 

Eh, you'll lose maybe 5 hp between a high flow cat and catless. It really just comes down to price and if you are willing to pay extra for the cat . I had a high flow catted dp on my SS/TC because I was only running GMS1 and didn't want to get an aftermarket tune to turn off the CEL for catless or chance running it and getting the light.

Your O2 sensor will read just fine no matter which route you go.

 

Get the angled bung whichever way you go. I did not with the zzp 400 cell catted dp and I had to tune out the code. Zzp 400 cell cat sounds just barely diff than stock. A slight rumble down low, but WOT almost the same.

 

Okay so 5hp no biggy...cost no problem...so which one would you suggest...does the TurboXS flow as good as the ZZP catted? Or is there a better one?

 

So the defouler/angled bung will avoid the CEL in the catted DP - correct?

 

They are both the same. I believe both even use a 400 cel cat. Both come with the angled O2 bung. I've owned downpipes from both brands. TurboXS is polished up nice, ZZP's isn't. That's pretty much the only difference .

The cat is what will prevent the CEL, but both ZZP and TurboXS have angled bungs in their downpipes because the O2 sensor has to be moved further down the downpipe so that it's behind the cat.

 

Confused regarding the RPD and wideband 02.....I read some posts where some guys with SS TC were placing bungs for the wideband. Is that because they do not have the RPD?
Is our wideband w/RPD not on the downpipe?

 

Nice was actually about to start a thread to ask about turboxs and zzp DP and I want to go the same route with turboxs FL exhaust with me money isnt the problem either I just dont want have a hard time passing emissions

 

Awesome....maybe we can figure this out together...

Sounds like the TurboXPS catted DP will look better, flow just as well as the ZZP, and since its Turbo XPS also ...less chance of fitment issues...plus wont stink up your cabin like a catless DP will...

 

My 400 cell zzp dp (no angled bung) still sets off p0420 low cat efficiency code.

Go angled bung, lucky I can tune out code for emissions, super easy fix.

 

Interesting. I was under the impression all ZZP catted downpipes had the extended bung. Might be something a potential buyer should message ZZP about to double check.

You might be confused with the SS/SC guys. All SS/TCs have a wideband O2, regardless of the RPD option. The SS/SC guys have to add a wideband in order to be able to log and tune effectively. Modern performance sells a downpipe with a handful of extra fittings, but the only time you would need them would be if you are adding an EGT sensor or a stand-alone wideband for a dedicated afr gauge.

 

Well im leaning into getting turboxs catted DP or even maybe the catless either way im getting a tune so code isnt really a problem. The only thing is emissions and by the looks of it in texas or in el paso they do an obdII check and a tsi check but the tsi is only done on older cars so im thinking of going catless instead

 

Well, that is why I mentioned this: Universal Exhaust Items - Vibrant Oxygen Sensor Defouler
Just screw it in ...same thing as an angled extended bung...we used to avoid CELS with that on our SRT4s no tuning out CELS ...


Probably, the guy asking the question in the link below had a 2009 Cobalt so ...maybe he had a pre 2008 balt and bought a new one...????
https://www.cobaltss.net/forums/forc...d-bung-237196/

 

^That guy has a 2009 Cobalt LS. He picked up a complete turbo kit from ZZP and they didn't weld in an extra bung for his wideband sensor. If you click on his profile, it says LS.

 

I could be wrong but I dont think that is correct. Im pretty sure I read on here that the angled o2 bung was to move the sensor out of the direct stream of HOT air thus preventing the low cat performance cel

 

This is truth ^^^ we used an angled bung (defouler) on the SRT4 for one reason only... to avoid the CEL. By pulling the O2 sensor away from the flow of the exhaust it shows less gas being detectable and fools the ECU into thinking that you have a full OEM cat on...

Information:

"The reason why your OBD-II diagnostic systems report this error code is because the 02 sensors detect an above normal exhaust reading when compared to OEM catalytic converter. The OEM catalytic converter does an excellent job at filtering/cleaning/converting exhaust fumes into cleaner air. The DME/ECU calibrates its post-cat sensors to the OEM catalytic converter performance and specs. Therefore, aftermarket cats do not clean well enough to satisfy the catalytic efficiency monitoring of the DME. This is a very common problem with aftermarket cats especially the high-flow ones.
Solution: By installing the defouler, you are in essence moving the rear 02 sensor out of the direct flow of the exhaust stream/flow. By doing so, you are tricking the 02 sensor with an inaccurate reading. Since the 02 sensors is not directly in the path of the exhaust fumes, it can not accurate measure the exhaust fumes."

 

I run a zzp Catless downpipe and turbo xs rfl exhaust. No fitment issues and no smelling issues. Just put it in right. I also suggest if you plan on doing rotated mounts, do them when doing the downpipe because the downpipe out of the car is easier to do the rear spacer or whole mount.

I used a defouler myself on my Catless, no CEL and no smells inside the cabin, not even bad behind the car. Car idles at 14.8 a/f ratio.

 

Ok!....that explains it!! THANKS

 

Here is proof that the extended bung is not for fitment issues on the cobalt but is to avoid the CEL:

Straight from TurboXS web page...

"This downpipe gives your Cobalt SS the ultimate in free-flowing performance! Full 3 inch T304 Stainless Steel piping is used for maximum exhaust gas flow. We even extended the rear oxygen sensor bung so you should be able to avoid that annoying CEL (Check Engine Light). You're welcome! "

 

For zzp DP do you need to buy that extend harness for the o2?

 

No. Plus if you use the defouler, it'll bring the o2 hole closer to the sensor

 

Where can I get a defouler from? Or what defouler you recommend ? Also kinda lost on the turboxs downpipes they have 2 different dp and on both you can get catted or catless anyone know the difference other than a 100$ difference es?

 

if you come from the SRT4 camp, why not support a familiar name?

Modern Performance!

No offense to the other guys, but I have had nothing but good delaings with them;
My brother runs a bunch of their stuff on his C-SRT4, and I have their catless downpipe.

My catless dp was from an early batch, so I ended up buying a defouler from them, but iirc they all come with defoulers now already welded on.

IMHO;
1) their exhaust is probably the best; it was designed to give more clearance than the competition, which is a biggy if you are, or intend to be lowered...
2) their interccoler is the best; It provides better than stock clearance, and is 100% bolt on with no adapters ect needed.

ZZP is great, and they offer many unique parts for our cars, but they are by no means the only go-to vendor ~ especially since you're already in Texxas (read: cheaper shipping from MPx as they're in Huston, and ZZP is way up by Chicago-land).