2.4L Performance Tech 16 valve 172 hp EcoTec with 162 lb-ft of torque

GMPP exhaust on 2.4?

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Old 06-13-2012 | 04:44 PM
  #11  
whitelightnin's Avatar
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sounds like me and you are in the same boat chef, nothing too loud and dont want to spend a fortune for sound!
Old 06-14-2012 | 02:16 AM
  #12  
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Im getting a stock exhaust off a cobalt ss/sc, its larger diameter and less restrictive muffler, see how it works out.
Old 06-14-2012 | 08:09 AM
  #13  
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cool! let me know how that works! i wish i could get my hands on a stock solstice exhaust!!
Old 06-14-2012 | 10:11 AM
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Originally Posted by prod
Im getting a stock exhaust off a cobalt ss/sc, its larger diameter and less restrictive muffler, see how it works out.
prod, the HHR 2.4 and Cobalt SS/SC catbacks are much more similar than you'd think! The resonators are identical in dimension.

Behind the resonator, the HHR necks down immediately to 2.25", where the Cobalt necks down to 2.25" in the portion over the twist beam. Just a short length difference there!

The mufflers (both) are 2.25" inlet. Construction is the same and NOT restrictive!

The Cobalt pipe to tip is longer than the HHR due to body differences.

IMHO, not really worth it!
Old 06-14-2012 | 12:32 PM
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Isn't the intermediate pipe on the HHR longer too Joe, I seem to remember there being a need to splice in a 5-8" length of tubing to make things all fit right.
Old 06-14-2012 | 03:08 PM
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Originally Posted by 843de
Isn't the intermediate pipe on the HHR longer too Joe, I seem to remember there being a need to splice in a 5-8" length of tubing to make things all fit right.
Not sure what you mean by "intermediate pipe", Mike.

FYI for everyone....

The earlier HHR 2.4 and Cobalt SCs used the exact same manifold. It flows better than most think!

The Cobalt SC downpipe is larger than the HHR 2.4 and necks down just before the catback flange. On HHRs, the downpipe is slightly different for auto and manual trans due to engine "clocking". Never had a chance to compare.

The only dimensional difference in the catback is behind the muffler.

As for the hangers, the front one, at the back of the resonator is the same. The others, I'm not sure of.

As for the muffler itself, years ago, before the SC, I put a straight through Magnaflow on the wagon. At that time I only had my tune. No other changes. Dyno showed absolutely no gain! Which made be take a cut off saw to the "turtle". There's a pic in my gallery. So, if anyone uses words such as "the restrictive stock muffler", get ready for a digital arse whuppin'!!

And, if anyone mentions "back pressure" as being a good thing.... Well, I'll probably get banned.

Exhaust is all about flow and maintaining velocity for cylinder scavenging. Yet some, especially the kidz on CSS.net, seem to think bigger is better! Currently the fastest street SC Cobalt is a friend that I've tuned for years now (and currently porting his cylinder head) that turned 12.0 @ 117 in the 1/4 mi. His exhaust is a 2-1/4" GMPP catback!

BOTTOM LINE: For the 2.4s the stock exhaust is plenty for anything other than a highly modified car. It just works! Anything else is money wasted or just noise!
Old 06-14-2012 | 03:12 PM
  #17  
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Originally Posted by chefhhr
Yeah for the price I'll probably just go with the Imco. I've heard good things about them before and at least a few members here are running them. The magnaflow universals are not really what I'm looking for sound wise and I just can't spend 5 bills on an exhaust...maybe much later down the road.
I bought it from Midas here in Hemet total installed and all welded $75.00

Last edited by jay loukakis; 06-14-2012 at 03:13 PM. Reason: most members are going with the Imco T-740 about 3 inches longer.
Old 06-14-2012 | 03:14 PM
  #18  
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The intermediate pipe is located between the flange at the end of the downpipe and the muffler, I thought that there was a length difference between the Cobalt systems and the HHR, maybe its a faulty memory Joe.
Old 06-14-2012 | 03:23 PM
  #19  
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Originally Posted by 843de
The intermediate pipe is located between the flange at the end of the downpipe and the muffler, I thought that there was a length difference between the Cobalt systems and the HHR, maybe its a faulty memory Joe.
Shoot, Mike.... You're not as old as me, but I am going to accuse you of "faulty memory"!

From the flange at the end of the downpipe to the end of the system at the tip, it is all one welded assembly.

Not sure about other Deltas, but I think I recall where some platform other than the Cobalt had a length issue, maybe Saturn. And, before you say faulty memory.....
Old 06-14-2012 | 03:26 PM
  #20  
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Originally Posted by jay loukakis
I bought it from Midas here in Hemet total installed and all welded $75.00
IMCO is just a junk replacement. Louder than OEM and no better for flow. Nobody has ever produced any evidence of a gain!



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