Prerunnerparts.com

[GhostX]

The headers and cat back exhaust systems here looked interesting.

http://www.prerunnerparts.com/new_products

Any thoughts or experiences with this type of modification and maintaining the "smog legal" status?

[Phall92139]

Yeah, those look like well designed breathers.  According to the Doug Thorley web site, all of their headers are 50-state legal and have the California Air Resources Board (CARB) number stamped on a tab welded to the headers.

I haven't had my Xterra long enough to really get familiar with the engine yet but normally speaking, the engine is just a big air pump and almost anything you can do to get more air in and more air out will have some benefit.  Have you seen the 4.0 OEM exhaust manifold?  Does it look fairly free-flowing or is a restrictive piece of cast crap?

[superslidestyle]

They are actually not cast, but made of welded tubing nicely welded but poorly bent with the stock cats welded on them.  I know that the 1st Gen Xterra could benefit substantially from a good set of aftermarket stainless steel shorty headers.  The flow on the stock cast pieces is absolutely horrible.  Unfortunately Doug Thorley has denied us!

[GhostX]

I studied a couple of threads on these on thenewx, and it seems like a worthy project.  I spoke to my mechanic and he agreed.

Rook on thenewx installed them himself and it took about 8-12 hours, and careful use of tin snips to remove a passenger side heat shield.   All of the reviews seem to be positive, and that they are 50 state legal makes them doubly nice for good ole Cal-if-orni-yay!