I'd be interested in hearing a sound clip of this if you get it done...2.4 sounds pretty throaty for a 4pot and has a little bit of burbble to it stock. Just afraid it would get ricey/farty with headers and exhaust...

 

I can confirm that the Hahn, Clear Image and Vibrant fit. Had the chance to try the JBP, but declined and that turned out with testing to be junk. Also had a Megan prototype, junk also. Stuck with the Vibrant for now.

One thing to note is that the engine/trans is "clocked" differently between the manual and auto. And on mine, I've rotated my assembly to deal with wheel hop issues. Those could result in clearance issues. Not sure.

I worked with a highly modified Cobalt owner (322 HP LSJ) testing these. There were some surprises, notably that the stock manifold put down some serious numbers. The JBP lost considerable power. Real gains with the good ones were small. Just don't believe the hype from those who sell this stuff.

 

Header alone doesn't make a big difference in sound. The rest of the exhaust certainly will. A LONG time ago I did some testing on backpressure with a few mufflers. The big surprise was how efficient the stock one was. Ended up gutting that out of curiosity.

 

Oh, the above pic...

Inlet on left and it's upside down.

Ended up (at that time) with a Magnaflow and got NO gain on the dyno.

Current system is larger and custom.

 

Interesting stock muffler we have...I had headers and full exhaust on my SC2. Was too loud so I added a 36" Thrush glass pack after the cat, helped to quiet it down (that and the silencer in the muffler). I'd like to do an exhaust on the HHR, but I've heard too many that sound bad. Not to mention it's my dd and I did the loud exhaust thing for too long. I agree that the rest of the exhaust and specifically the muffler make the majority of the sound, just wondered if the headers would make any further, noticible difference.

 

Most folks I have talked to claim their header makes their car sound ricey. Well actually it is the lack of cat or addition to high flow cat, I think. But these days they seem to be a package most of the time. I bought my header/dp used from a forum member. He had a lot of trouble with the sound. Said it was ricey. Took the chance and noticed pre install some reference parts that were dark from leeking. Addressed those issues on install. No problems.

From what I can see a lot of the complaints on sound are the turbo muffler and stock muffler guys. I assume the high flow cat or cat delete increases exhaust speed that picks up a whine. Mine did change sound as well. I have a ss packed muffler. It was supposed to be a magnaflow but wrong part was delivered and I can't remember what it is. At any rate stock it sounded like an old school 289 with the new muffler. Now with ca intake, cams, tune, throttle body, headers, dp with cat, shaved head and port and polish on head and header it sounds like a 289 hi po when the 4 barrel kicks in on wot. Very fast throttle response and pulls strong through gears. Sounds like a hp engine. Does not sound like a ricer with a fart can. Low rpm it does drone and resonate in the interior, so most would not like it. It sounds like my 66 mustang. It has had the electric shift kit on it for a long time now. Stock it could get 1st to second rubber. Now it can burn 1st to second with a 10 foot mark, hit 2nd to 3rd hard enough to studder the tc and chirp 3rd to 4th. Not bad at all for a little grocery getter with a 4 banger.

 

If it doesn't sound llike a ricer with the fart I wonder what it can be. I doubted Flowmaster but again the HP have me confused.