I am doing a 4.0 Head conversion and need to install a new manifold/header. They sure can be expensive. Here is a link to an OE replacement manifold. Has anyone used this? Its very similar to Borla, Thorley, Banks, etc. Was there performance gain? What headers have you had good luck with?
Link- http://www.autopn.com/store/pc/viewprd.asp?idProduct=20009

A stock exhaust manifold is very different than a performance header. You need to buy one of the 300-400$ borla or gibson headers before you will notice any power, and it won't be more than 7-9 HP.

Yep! What Sunder said.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

I could not agree more that stock exhaust manifolds are much different than performance headers and to take it a bit further stock manifolds alone run the gamit of different levels of realized performance enhancements. But what I was looking for was an opionion of the exhaust header/manifold that I had linked to and the other types of header/manifolds such as Borla, Thorly, Banks etc. Here are few more links, see the resemblance? Any change in your opinion? Do you think the header at Auto Parts Network is a good deal for the performance vs. $$ ?
Thanks.
http://www.autopn.com/store/pc/viewprd.asp?idProduct=20009
http://www.prostreetonline.com/buy/borla%5Fexhaust%5Fheader/jeep/
http://www.rocky-road.com/xjthorley.html
http://www.bankspower.com/System.cfm?appid=AJ01&sysid=SJ01

I would go for the Banks if I had the money! Stainless and has a solid bar to help hold the pipes in place when expanding and contracting.
The Tocky Road one has something near the banks. But this feature only MIGHT keep the manifold from leaking at the head.
As far as which will develope more horsepower? I doubt in normal driving you could tell the difference. On the strip you might find 6' between them in a 1/4 mile.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />