I have an '06 with kooks and stock mufflers.. Sounds about the same as stock for me, but there is a little more growl both in the cabin and out the exhaust once you get up to the 2.5k-3k rpm range.

 

...that is why the LS7 exhaust manifolds with headpipes are starting to look like a good alternative on a cost versus benefit ratio.

 

I agree.
The 2008 LS3 sounds about the same as stock, but once you reach 3k rpm it has a better growl.

 

I totally agree with that, you can pick up a good set of used exhaust from a Z and get pretty much the same result as headers for hardly any money! Which again proves my theory that LS7 manifolds seem to flow as good as headers!

 

Why would you install headers and not tune? How would you expect the engine to compensate for the extra air flow? A tune alone will NOT give you the same gains as headers and a tune, not even close. That's kind of like saying you should just be able to change the cam and not tune and see good power gains, but it doesn't work like that...the computer is not that smart or flexible. In fact, adding headers WITHOUT tuning is not a smart or safe thing to do from an A/F point of view.

There apparently was a problem with the air intake as stated by the shop (which the OP did not mention) but I have to tell you...out of all the headers we have installed, regardless of brand or LS series, we've always seen good gains of about 20-30hp...including cars that were already tuned and just had to be tweaked for the headers themselves. I think any of the other shops or owners will agree with me as well.

 

My car made 395 hp stock. After we bolted on the headers, we let it run for 15 min or so to get all the oil burned out of the headers/xpipe so I assume the car did some tuning on its own during that period. First run back on the dyno showed 416 hp. Post tune the car made 424hp/418tq.

 

I will say this.

There was a problem with the air intake and some tuning issues that Lg Motorsports corrected for me.

So my intake problem and my tuning issues was worth say 1-2 hp and that means the headers picked up say 2-3 hp. Are you can say this, with the air intake fixed and tuning issues fixed and Pro Long Tubes Headers added to my car I picked up a total of 5 hp. So, I don’t see how a car that already been tune and just needs to be tweaked still gain 20-30 hp after adding headers.

Again not trying to start anything just stating what I know and understand

 

LS3 stock 392/378

LG Headers, Vararam & Tune by CoW 416/416 (and thats w/4.10s)

 

I understand you are not start anything, and we are just trying to help, please dont take any of this negatively, it's certainly not meant that way.

Again...look at your midband increase.... Thats coming from the header....and you'll feel that on the street a lot more than you will a peak number. Headers allow the car to breathe better, but they are not "power adders" in the same vane as a turbo or supercharger that will up your peak HP. They are allowing your "stock" components do the best they can do, and the stock cam, intake manifold and TB can only do so much. If the engine's stock parts are running out of breath by about 5800 or so, the headers can't do anything about that. Think of the headers as just what you described, a foundation and support for your cam and other mods, while giving you a big midrange boost in the area that you drive the car the most.

A few questions: Make believe for a minute that didn't see the before/after dyno, how would you say the car performs with the headers? Is it more responsive? Smooth? Does it come alive earlier in the powerband? After the dyno tune, did anyone do any on road logging and tweaking to help compensate for the Vararam's extra airflow at speed? Do you have the A/F ratios from the dyno chart?

In regards to your tune, you state LG fixed a few tuning issues. Was the car already tuned when you got the 160 stat? A comprehensive tune from stock to an after a header install would take a while...it would be more than just fixing a "few" issues... If you can give us some more information, maybe we can explain better or find out if there's something else going on.

 

Yes, the car is more responsive and smoother.
I can not really tell if the power band is earlier are not. I can tell I picked up some but it’s not a kick in the butt.
There was no road logging and tweaking to help compensate for the Vararam's. No A/F ratios were provided.
I also agree with it’s the foundation for future mods and give the most in the midrange. That’s why I looked for the Curve more then anything else, but it was not what I was expecting, from what I have read what everyone else is getting with the same mods.

The only thing I can think of is I went from Gutted Cats –to- Headers with Cats, so not gaining as much as someone with a stock exhaust. With gutted cats my car made more Hp then people would think. Say this, Gutted Cats make 5-7 hp, then you exchange for headers with cats and only pick up 5hp that would make say 12 hp and the Tq would do the same. Who knows~!

The tune was done when it was stock. Mod’s added after tune was 160% T, Vararam, Gutted Cats.

 

ls3 A6 stock i dont know

cold air, tune 400/387

cold air, headers w/cats (stock cat back), tune 429/413

 

i would be interested in hearing about this too, im suposed to be getting AR headers done very soon, this is getting me nervise lol