I'm thinking of doing the header thing to my C6. I haven't put headers on anything since 1973, because when I did it then they plain old sucked, didn't fit right, rotted out, constantly making pinging noises and I never felt any noticable power gains from them. So, I'm older and not necessarily wiser but from the posts I read here it appears that they are the best bang for the buck.
So my questions are:
Which brand?
What else do I need (I need the CATs)?
What size (I'm pondering adding an SC down the road)?
Do the stock mufflers limit power gains with headers?

Also what are any downsides I should be prepared for with headers?

 

There are many good brands. It's more of a personal choice. LG, Kooks, American Racing seem to be the most used now. LG offers a little more TQ due to the longer primaries. You might want to ceramic coat them to avoid a CEL.

All of them use an x-pipe with cats or an "off road" version without cats. I would get the cats.

1 3/4 is the best all around size. You may get a little more HP with the 1 7/8's when you add the SC, but you'll be loosing some until you get it.

The stock muffs flow well, and I would see how you like the sound before changing them.

Downsides: You may hear some pinging. Not sure about the smog laws in Mass, and what they'll be in six years, when you have to smog it. It should pass the sniffer with cats. CEL light-ceramic coat 'em.

 

I was the same place you are 2 years ago. I've got headers on my Hurst/Olds and I replace the gaskets every other year. I was against headers until my buddies told me they are better built now days. And they are. The new Stainless headers are night and day better for fit and sealing (and 4 times more expensive). I've never had a leak on either Vette and none of my friends have either. Most will tell you to go 1 3/4 and header wars are one of the most common threads out here.

I like my American Racing headers very much, just installed them. I did have to bend the heat shield on the right side of the car where the firewall meets the floor pan, it was too tight there and hit when I revved the car up, but it's fine now with a little persuasion. They make your exhaust about twice as loud, so buy headers before you buy a cat back or you might be sorry if you don't like loud. I had headers with Borla Stingers and they were LOUD. Almost too loud. But I got used to it. I've got Magnaflow 14336's on my C6 and they got twice as loud. Might be too 'droney' now, I haven't decided yet. Stock mufflers won't hurt power from what I've read. I get cats every time, I daily drive my car and can't be walking around in a suit smelling like a gas station like you do with no cats and top down. At 370 rwhp before tune and 424 rwhp after tune I don't think the cats are hurting my much. And you do feel the difference from adding headers to a Vette. You do hear the "pinging" of the combustion a lot more with headers, but I like that.

IMHO, gears, at about the same price, are a better SOTP mod, they are unbelievable. But if you're going FI someday, and plan to 1/4 mile, you probably don't want gears. A tune to get rid of Torque Management is 2nd best mod (but get that when you're done with other mods), and headers are a close 3rd. A tune really wakes up the headers too.

Long winded answer, and just my opinions having owned a H/C C5 and a stock internals C6.

 

Thanks Tommy, one question, why would I get a CEL from headers, and how will a Ceramic coating prevent it?

 

Due to the cats being located farther away from the exhaust ports, the exhaust gasses are able to cool and the cats don't 'light" quick enough. On some cars this causes a CEL. The coating insulates the gasses and keeps them hot enough to light the cats quickly. Lot's of other benefits also. www.Jet-Hot.com

 

The American racing headers are an easy install, no CEL after several months. I did not ceramic coat them as the staff at AHR said it really isn't needed. If you go with AHR save the money for the ceramic coating it really isn't needed, unless you want it for the looks.

 

I have read some arguments over the 1 3/4 vs 1 7/8 size a while back, since the Magnacharger is still in the Pipedream phase and my goal is mostly low end street SOTP driving, I'll probably do the 1 3/4.

I think the pinging I used to hear was more like the headers expanding and contracting. I forgot all about the header gasket thing until you reminded me.

I have thought about gears, and if I did not have a Z51 MN6 I might have already gone there. I'm concerned they might make it too low in the lower gears. I've got to find a local tuner before I begin all this.
Thanks

 

I just purchased the 1-7/8 headers. Didn't really plan on upgrading anything else except the air intake system (Vararam and maybe an upgraded mass airflow sensor). Horsepower Engineering did not indicate to me that there could be a loss in horsepower? Is this true, I was planning on picking up 10 or 20 horsepower???

 

My American Racing headers lit up a PO00430 code all the time until I had it tuned out. I'd reset it and every day it would come back during my dailly drive. maybe I was unlucky but a tune taks care of it.