I've looked at several brands of headers over the years, but always had concerns about the complexity of the install, and the $1000 plus price tag.
I have Mike in AZ's GHL Old School true dual exhaust system which mates perfectly to the stock manifolds, and hated to spend a bunch more money cutting it up to work with headers.
Kooks no longer has the 1 3/4 system available, and according to Mike, the 1 7/8 system is a bear to install.
I also have the C6 oil pan, which apparently has fitment issues with the Kooks headers. Not sure about other header designs because I haven't read anything regarding any fit issues with the C6 pan.
I also had some doubts due to the excessive underhood heat possibly affecting the clutch line, or as has happened to others, damaging the power steering lines.
When I removed the stock exhaust system, I was surprised at the relatively smooth flowing design - not at all what I expected.
I did some research, and found the following thread, in which Art (hdflstf) and Jim Gnitecki discussed cams, heads, headers and stock exhaust systems.
I was encouraged by the information, and with some further searching, found an interesting video on how to improve the flow of the stock manifolds. The information there was very similar to what Art said. A photo of what Art had done to his manifolds is below.
I then phoned Mike in AZ, and left a message asking for his opinion on whether it was worth it to ceramic coat my stock manifolds inside and out. Would ceramic coating decrease underhood temperature and possibly improve flow?
Mike called me back a half hour later, and emailed some photos of a ceramic coated set of exhaust manifolds done in his favorite titanium color, and chrome colored ceramic shields. He made me a deal I couldn't refuse, and the manifolds were on their way. I now have them in my garage, ready to install when the engine gets back. Even if they don't provide any improvement in underhood temperature, they are drop dead gorgeous.
Once the engine is back, I'll see if it's worth it to grind a bit of the roof of each exhaust port to better match the top of each head port. The old gaskets are perfect for a pattern.
After reading some info regarding broken manifold bolts, I decided to upgrade to ARP bolts.
One thing that was important to me because of my limited abilities was to carefully document of all the nuts, bolts and other fasteners so I wouldn't lose track of where they all went. I'm glad I did, because one comment Art made in his head and cam thread was concerning the problem he had trying to rotate the engine with the new cam installed. One bolt the wrong length got in the way.
Someone I know who just went through getting an engine re and re at at local shop found that the mechanic there had all the nuts and bolts in a bucket, and some of them ended up in the wrong place during reassembly.
First photo is of Art's manifold after he did some grinding to smooth out the roof of each port.
Second photo is of the ceramic coated stock manifolds Mike in AZ shipped me.
Third photo is of the nuts and bolts drawer.
Fourth photo is the backside of the two manifolds.