These headers are by far the best bang-for-your-buck exhaust part you could get for a DE-engined 350Z. The headers flow really well, and actually performed better than the crappy ebay tubular headers I had on before them. Do note that this mod does require you to actually change the position of the exhaust manifold studs on your heads, which is easily doable while the motor is still in the car but it's a pain and WILL result in bleeding hands from accidentally cutting yourself against the studs. It hurts.
Also note that the DE and HR headers have different outlet flanges, so you'll need HR cats or HR test pipes as well.