I've been thinking about doing some exhaust work to my car. I don't want to change the cat back because I'm not lookin to change the sound by much at least.

I was thinking about changing the down pipe. Do any of you guys just have a down pipe (catted or not) with the stock exhaust? And if so do you feel it was worth it? I know if I change the whole exhaust I'll feel a difference but I don't want the sound.

I hear the the down pipe is where most of the restriction is in our cars and that the cat back isn't that bad.

 

A cat back adds 5 whp (so yes the factory exhaust is not very restrictive), any of the down pipes that are made to fit the cobalt ss/tc fits the hhr ss.

A couple of other popular manufacturers besides Hahn are:
ZZP Performance
Clear Image Automotive

Go read this link, very informative and it applies to the HHR SS as well.
http://www.cobaltss.net/forums/showthread.php?t=198998

 

Do you have the GM turbro upgrade? Otherwise, the system will learn down your modifications to the production power levels.

 

i have the ZZP with stock exhaust. a little buzzy during start up but once shes warmed up you cant even hear it. cruising the higway or your neighborhood, you forget its even on. WOT, it reminds you that it is.

great quality. great price. under $300 including shipping.

 

Yes I have the GM stage upgrade and HP tuners. Plus the K&N intake, Hahn pipes and intercooler. I'm currently making 299hp at the wheels and 335 tq. So if all I can gain is 5hp from a full exhaust then I think I'll just leave it. I really don't want the noise. I've had that on cars in the past and one of the reasons I got the HHR was to just have a nice daily car with some fun and tunability. I might then just save the money and put it towards a clutch and flywheel cause mine slips now.

 

If you would get the Hahn cat back, make sure you check out www.TurboTechRacing.com, we have them at the best price. Also so you know the cobalt and HHR SS turbo downpipe are the same part.

 

Explain learn down please,

 

If you dont have the stage kit or any kind of a tune the modifications will not do anything for you because the comuter learns itself back to stock levels.

And a catless downpipe can give you up to 15whp. Its extremely restrictive

 

If I change the down pipe I would go with the catted one. If that alone will give me around 10 hp then I would consider it. But for any less it''s not really worth it.

Thanks for that link HHRSSouth it was a good read and I think it might have swayed my dicission in to getting a new catted down pipe. I never really thought about the fact that there are 2 cats there and that the o2 is restricted at that point. I could see the benifits in changing it out.

 

My old employer, Stainless Works in Cleveland makes a DP for the HHR SS. Highest quality TIG welded 304 stainless, and they do all their own fabrication, giving them a price advantage over speed shops just branding someone else's work.