Before i got into hhr's i never heard of IMCO! But when it comes to exhast its name always comes up. What about using one from a common manufacturer. Dynomax. Flowmaster. Borla????

 

We already tried them. Basically, most "high performance" mufflers flow too much for the HHR's little Ecotec engine. It likes to see a bit more back pressure, and after testing many different mufflers, we found the best combination of power and mellow sound with the IMCO. It does not sound "ricey" like many small 4-bangers you hear.

If you choose to go with a "name brand" all you will get is lots of noise, increased droning inside the cabin, and a lack of bottom end when driving the car. We've done the testing so you can buy in confidence. (*BTW: IMCO is a highly repected name brand in the replacement muffler market.)

Hope it helps,

 

to the site.I have found the search tool to be the answer to most of my questions.I searched "IMCO" and found this thread that might answer your concerns.There is a wealth of information to be found here at this forum.Again welcome. https://www.chevyhhr.net/forums/show...highlight=IMCO

 

I will agree with most of what Mike says.

For the money, I don't think you can do better than the IMCO!!

I really enjoyed mine while I had it. I liked the bit of a growl that I got and it did perform better.

I now have a custom system. Lots more money, and in my opinion, lots more performance! Back pressure was important in what we did and it turned out well. Much loader than the IMCO, great for me, but we wouldn't do this in my wife's HHR! No dyno's, but I feel I have more power now than with the IMCO.

So let me repeat.....

For the money, I don't think you can do better than the IMCO!!

 

hmmmm. IMCO it is. thanks guys

 

I have one on NEMO, also have the CGS intake with the outlaw filter.
Sounds GREAT, and added power.

 

The infamous IMCO is an old fashion multi-chambered "turbo" type muffler, which was nothing more than an old school reverse flow with larger passages.

The BS you read about "backpressure" and the HHR's need for that is nothing more than BS.... Backpressure is resistance to flow!!

If you want to make power, you have to flow MORE NOT LESS!!

For those who want to know, the STOCK 2.4 muffler has 12% LESS backpressure than the IMCO T924. It is a pretty efficient design. This testing was done with pressure pickup point located just in front of the muffler. A couple of us engineers tested 3 different mufflers besides the OEM. The IMCO went back into the box!!

The "secret" to a good power band is to maintain a good velocity in the exhaust system, at about 240 CFM. Choke it with more backpressure and you lose power.

The major problem some run into is with a larger diameter system, typical of many cat-backs on the market. The increase in size reduces velocity and flow and scavenging is comprimised. While top end HP may increase, there is a loss of low to mid-range power, which is the band through which you accelerate and operate most of the time.

Now "noise" is a totally different issue and many perceive more noise as more power... and often falsely.

Folks, read up on efficient exhaust systems! There's lots of info out there. Or take a Master's level course in Fluid Dynamics.

Now.... who wants to discuss hot air intakes and how they can lose power?? (with actual dyno charts!!)

 

SoCalHHR's and JoeR....

I find both your posts informative but lets not start those wars again!

Each has their opinion and it has been stated. Rebuttals on this topic tend to end up agrumentive and non-productive.

 

I'm not going to say what is better then the other. I had a flowmaster super 40 on my 2.2L and I loved it. It was a bit loud on the highway, but i didnt care. I now have a straight pipe set up. Cat was cut open and cleaned out, rez is still on, but not for long and the muffler was replaced with functional side pipes. I am loving my exhaust now!!!!!!

I'd say do what you want. I'm not sure my side pipes are the best for performance, but they look and sound sweet and it is for sure pulling harder the when it was a stock system.

 

Joe - don't be an idiot. You're talking about something that pertains to V8's only. Read up a bit on 4-cylinder engines - they need BACKPRESSURE to make power. Without it, they simply fall on their face. Any engine builder worth his salt will tell you; a 2 1/4" exhaust system is good for up to 500hp. Why are all the new truck systems 4 and 5 inch? Because "bigger sells." And that's the truth. Put a flowmaster, dynomax, Gibson or whatever on your ride and all you're going to get is NOISE! the HHR will be a gutless wonder with no bottom end, and the cab resonance will drive you crazy (although the civic owners will probably think you're cool!).

But then, you're the expert - right?

Oh, and if you want to read how HOT air short ram intakes make MUCH more power than cold-air long ram designs - do some research on the net, there are tons of articles about it out there. Ask anyone at any air intake company who designs them (not the "marketing guys" who sell them!) My former boss, who now owns TPR, did a massive lab shootout last year that debuked the "cold-air" theories.

Read about it here: TPR Intake Lab

Let me know when you change your line of work - I've been in this industry for over 20-years....