cobalt123
Platinum Member
saw this elsewhere and it NEEDS to be read by all noob lnf owners props to who made it
What is a Downpipe?
The downpipe is the portion of the exhaust that connects the turbo to the rest of the exhaust system (cat-back exhaust). On our cars the dowpipe comes from the factory with two Catalytic Converters on it (more on Catalytic Converters http://en.wikipedia.org/wiki/Catalytic_converter) their main purpose is to help reduce the emissions coming out of the tail pipe, because of this they do restrict the flow of exhaust gases and because were all about making more power that's a bad thing. The stock/factory downpipe is the most restrictive component in our exhaust system. Replacing the downpipe with an aftermarket unit will greatly improve the flow of exhaust gasses out of the engine and in turn help us make more power (I've heard anywhere from 10-15 horsepower and 10-15 ft/lbs of torque). Below is a picture of a stock downpipe from a 2008-2010 Cobalt SS Turbo
If you plan on upgrading you basically have 2 main options here and they are as follows:
Catted Downpipe
An aftermarket catted downpipe may be purchased, these downpipes remove the (2) stock factory Catalytic Converters and replace them with one High Flowing unit, these downpipes also get rid of that little dimple you see by the O2 bung (which also reduces flow). If you have strict emissions laws in your state/province this is probably going to be your best bet as the high flowing catalytic converter helps you meet your emisions targets but flows significantly more than the stock cats do. These downpipes are louder and in my opinion better sounding than the factory exhaust and they do improve exhaust gas flow and in turn help us make more horsepower.
(If anyone has a sound clip or video of a catted downpipe with a stock exhaust please let me know and I'll put it in)
CIA Shown
Catless Downpipe (commonly called Off-Road)
An aftermarket catless downpipe may be purchased, these downpipes remove the (2) stock factory Catalytic Converters and replace them with a straight mandrel bent 3" pipe they also remove the dimple you see by the O2 bung. If you don't have strict emissions laws in your state/province or your just a rebel this downpipe may be your best bet. These downpipes are a little louder than even the catted downpipe they provide more of a deeper gurgle type tone and yes they do improve exhaust gas flow and in turn help us make more horsepower, the catless downpipes can help us make an additional 1-3hp over an aftermarket catted downpipe because they have no cats at all.
http://www.youtube.com/watch?v=4Glk6jXowoA
http://www.youtube.com/watch?v=iw2ODRztqkg (Catless w/ Cutout Option)
(If anyone has more sound clips or videos of a caless downpipe with a stock exhaust please let me know and I'll put it in)
Video
OTTP Shown
Advantages of an Aftermarket Downpipe (catted and catless)
- Improved exhaust gas flow = more power
- Improved sound (Catless sounds great, Catted sounds great as-well but slightly muffled)
- Faster turbo spool up (slightly)
- Weight savings over stock downpipe
Disadvantages of an Aftermarket Downpipe (catted and catless)
- Potential of throwing a Check Engine Light (if catless) I'll talk more about this later
- Increased emissions (if catless)
- Possible odurs from exhaust (if catless)
- Cost
- Louder than stock
- Possible warranty issues
O2 Bung/Chamber
The O2 Bung/Chamber is the threaded hole where the Oxygen Sensor (O2 for short) sits. The design of it is important especially on a catless downpipe if the O2 sensor does not like what it's reading like when there is no Catalytic Converter infront of it it may trigger a Check Engine Light (CEL for short), which can be disabled via a code reader/clearer (can be picked up for relatively cheap) [if anyone has the link to the thread talking about CEL's for this please let me know]. If the thought of having to go get your CEL cleared scares you, you should probably just go the safe route and get a catted downpipe. Some vendors offer an angled O2 Bung/Chamber (usually for an extra cost $20-50) which limits the amount of exhaust gasses the O2 sensor sees this helps reduce the chances of getting a CEL especially with a catless downpipe I highly recommend getting the angled O2 chamber shown below:
OTTP Shown
Other things you should know about
Electric Cut-Out
Some vendors offer an option for an electric cut-out which is welded into the downpipe, what this does is let you via a switch mounted in the cabin by-pass the whole cat-back exhaust and vent your exhaust gasses right at the downpipe this improves exhaust flow however it makes the exhaust very loud and should probably only be used at the track unless you want a nasty ticket.
Second O2 Bung
If you have a wideband that you want to use some vendors offer the option to weld in a second O2 bung into which the wideband can be plugged in. This second O2 Bung is welded in before the Catalytic Converter.
Aluminized or Stainless Steel
If your on a budget or you don't plan on keeping the car for very, very long you can go ahead and get an aluminized downpipe as it is cheaper because it is more prone to rust. However if you never want your downpipe to rust or stop looking pretty get stainless steel.
Spun Metal Cat
Smaller higher quality Catalytic Converter offered by some vendors.
Where can I buy an aftermarket downpipe?
There are many vendors that sell downpipes as far as I can tell there isn't a big difference in between them all the main one being catted or catless and O2 Bung/Chamber design options. Here is a list of the ones I have heard of (in alphabetical order to prove that I am not favoring a particular brand):
CIA (Clear Image Automotive)
http://www.clearimageautomotive.com/Products/Cobalt SS TC.htm
Catted, Catless, Electric Cut-Out, Aluminized or Steel Options
Dejon
http://cobalt.dejonpowerhouse.com/
Only Catless
Exhaust Depot
http://www.exhaustdepot.net/cosstudo.html
Catted or Catles Options
Hahn Racecraft
http://www.turbosystem.com/ProjectVehicles/New_Folder/Cobalt/CobaltTCdownpipe.htm
Lots of options
OTTP
http://www.ottperformance.com/store/pc/OTTP-LNF-Down-Pipe-27p908.htm
Catless, O2 Chamber Design, Wideband O2 Bung Options
Synapse Turbo
http://www.synapseturbo.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=SM&Category_Code=downpipegm
Only Catless
ZZP
http://www.zzperformance.com/cobalt_ion/products1.php?id=1016&catid=155
Catted, Catles, Spun Metal Cat, O2 Chamber Design, Wideband O2 Bung Options
(If I didn't list all of the vendors or some should be taken down please let me know, also if there is any information that is missing and or wrong please let me know and I will fix it)
What is a Downpipe?
The downpipe is the portion of the exhaust that connects the turbo to the rest of the exhaust system (cat-back exhaust). On our cars the dowpipe comes from the factory with two Catalytic Converters on it (more on Catalytic Converters http://en.wikipedia.org/wiki/Catalytic_converter) their main purpose is to help reduce the emissions coming out of the tail pipe, because of this they do restrict the flow of exhaust gases and because were all about making more power that's a bad thing. The stock/factory downpipe is the most restrictive component in our exhaust system. Replacing the downpipe with an aftermarket unit will greatly improve the flow of exhaust gasses out of the engine and in turn help us make more power (I've heard anywhere from 10-15 horsepower and 10-15 ft/lbs of torque). Below is a picture of a stock downpipe from a 2008-2010 Cobalt SS Turbo
If you plan on upgrading you basically have 2 main options here and they are as follows:
Catted Downpipe
An aftermarket catted downpipe may be purchased, these downpipes remove the (2) stock factory Catalytic Converters and replace them with one High Flowing unit, these downpipes also get rid of that little dimple you see by the O2 bung (which also reduces flow). If you have strict emissions laws in your state/province this is probably going to be your best bet as the high flowing catalytic converter helps you meet your emisions targets but flows significantly more than the stock cats do. These downpipes are louder and in my opinion better sounding than the factory exhaust and they do improve exhaust gas flow and in turn help us make more horsepower.
(If anyone has a sound clip or video of a catted downpipe with a stock exhaust please let me know and I'll put it in)
CIA Shown
Catless Downpipe (commonly called Off-Road)
An aftermarket catless downpipe may be purchased, these downpipes remove the (2) stock factory Catalytic Converters and replace them with a straight mandrel bent 3" pipe they also remove the dimple you see by the O2 bung. If you don't have strict emissions laws in your state/province or your just a rebel this downpipe may be your best bet. These downpipes are a little louder than even the catted downpipe they provide more of a deeper gurgle type tone and yes they do improve exhaust gas flow and in turn help us make more horsepower, the catless downpipes can help us make an additional 1-3hp over an aftermarket catted downpipe because they have no cats at all.
http://www.youtube.com/watch?v=4Glk6jXowoA
http://www.youtube.com/watch?v=iw2ODRztqkg (Catless w/ Cutout Option)
(If anyone has more sound clips or videos of a caless downpipe with a stock exhaust please let me know and I'll put it in)
Video
OTTP Shown
Advantages of an Aftermarket Downpipe (catted and catless)
- Improved exhaust gas flow = more power
- Improved sound (Catless sounds great, Catted sounds great as-well but slightly muffled)
- Faster turbo spool up (slightly)
- Weight savings over stock downpipe
Disadvantages of an Aftermarket Downpipe (catted and catless)
- Potential of throwing a Check Engine Light (if catless) I'll talk more about this later
- Increased emissions (if catless)
- Possible odurs from exhaust (if catless)
- Cost
- Louder than stock
- Possible warranty issues
O2 Bung/Chamber
The O2 Bung/Chamber is the threaded hole where the Oxygen Sensor (O2 for short) sits. The design of it is important especially on a catless downpipe if the O2 sensor does not like what it's reading like when there is no Catalytic Converter infront of it it may trigger a Check Engine Light (CEL for short), which can be disabled via a code reader/clearer (can be picked up for relatively cheap) [if anyone has the link to the thread talking about CEL's for this please let me know]. If the thought of having to go get your CEL cleared scares you, you should probably just go the safe route and get a catted downpipe. Some vendors offer an angled O2 Bung/Chamber (usually for an extra cost $20-50) which limits the amount of exhaust gasses the O2 sensor sees this helps reduce the chances of getting a CEL especially with a catless downpipe I highly recommend getting the angled O2 chamber shown below:
OTTP Shown
Other things you should know about
Electric Cut-Out
Some vendors offer an option for an electric cut-out which is welded into the downpipe, what this does is let you via a switch mounted in the cabin by-pass the whole cat-back exhaust and vent your exhaust gasses right at the downpipe this improves exhaust flow however it makes the exhaust very loud and should probably only be used at the track unless you want a nasty ticket.
Second O2 Bung
If you have a wideband that you want to use some vendors offer the option to weld in a second O2 bung into which the wideband can be plugged in. This second O2 Bung is welded in before the Catalytic Converter.
Aluminized or Stainless Steel
If your on a budget or you don't plan on keeping the car for very, very long you can go ahead and get an aluminized downpipe as it is cheaper because it is more prone to rust. However if you never want your downpipe to rust or stop looking pretty get stainless steel.
Spun Metal Cat
Smaller higher quality Catalytic Converter offered by some vendors.
Where can I buy an aftermarket downpipe?
There are many vendors that sell downpipes as far as I can tell there isn't a big difference in between them all the main one being catted or catless and O2 Bung/Chamber design options. Here is a list of the ones I have heard of (in alphabetical order to prove that I am not favoring a particular brand):
CIA (Clear Image Automotive)
http://www.clearimageautomotive.com/Products/Cobalt SS TC.htm
Catted, Catless, Electric Cut-Out, Aluminized or Steel Options
Dejon
http://cobalt.dejonpowerhouse.com/
Only Catless
Exhaust Depot
http://www.exhaustdepot.net/cosstudo.html
Catted or Catles Options
Hahn Racecraft
http://www.turbosystem.com/ProjectVehicles/New_Folder/Cobalt/CobaltTCdownpipe.htm
Lots of options
OTTP
http://www.ottperformance.com/store/pc/OTTP-LNF-Down-Pipe-27p908.htm
Catless, O2 Chamber Design, Wideband O2 Bung Options
Synapse Turbo
http://www.synapseturbo.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=SM&Category_Code=downpipegm
Only Catless
ZZP
http://www.zzperformance.com/cobalt_ion/products1.php?id=1016&catid=155
Catted, Catles, Spun Metal Cat, O2 Chamber Design, Wideband O2 Bung Options
(If I didn't list all of the vendors or some should be taken down please let me know, also if there is any information that is missing and or wrong please let me know and I will fix it)
