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It is a little easier to remove the stock exhaust manifolds on a 350Z than many V type engines. The passenger side can be removed without a lot of fuss right from the bottom of the car.
The driver side is a little harder due to the steering shaft being in the way. The front bolts have to be accessed from the top of the engine.
Howard Watanabe switches the O2 sensors from the stock manifolds to the DC Sports headers.
When compared directly you can see that the DC Sports headers have a lot more power potential than the log type stock exhaust manifolds. Individual primary tubes with near equal lengths are much more effective than the stock manifolds' very unequal pairings through small passages.
The passenger side header bolts in place easily and fits without issue.
The driver side header went in easily. An interesting thing to note is that there is plenty of clearance between the header and the steering shaft and rack. Many other headers hit in these areas because most companies don't realize that on a 350Z the engine can move around quite a bit on the motor mounts. Compounding the problem, the stock rack bushings allow quite a bit of movement as well.