I have Kooks 1 7/8's... And have had no leaking issues... The welds on the kooks headers are no less perfect than those on the ARH...

But I must say, headers is quite the waste of money, considering the cost:hp ratio... I needed some long tubes because I am running ported heads and cams, so they do more for me than they would do for a "normal" cobra. I wouldn't even waste my money on headers, unless you're pushing 600+rwhp...

 

Do yourself a favor and purchase the book title above. ISBN #1-932494-20-0. Author Richard Holdener covers just about every configuration you can come up with.

 

Headers gave me a decent gain...
Hooker LTs and O/R X Pipe on a GT went something like this.
Before - 353RWHP, 349RWTQ
After - 350RWHP, 371RWTQ
The lost horsepower was because after adding the exhaust, I lost 2 PSI boost (9PSI before, 7 after)