Yes, I have them and love them.
Install was a pain in the ass, but any LT install is going to be.
Yes, they have turned the colors you would expect them to turn. The headers aren't extremely visible though, so it's not like its a big deal. If it IS a big deal to you, have them Jet-Coated.
Absolutely NO leaks.
The variance of HP increases between any header brand is going to be very small. I doubt my OBX headers give me any more or less HP than, say, JBA, for example.
Hopefully that helps!
'02 Supercharged Harley-Davidson F-150 (Sold)
'05 Mustang GT (Sold)