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I installed both of these parts at the same time about a month ago so I will review them together. They went onto my 2013 G37S sedan with about 20k miles.
FIT/FINISH: I would say both of these parts are of very high quality. In the pictures below you will see that the ceramic coating on the headers has kept them looking like new while the cats have changed quite a bit in color due to the heat. They were both highly recommended by both vendors I talked with.
Everything fits fine, bolts up nicely, and the Z1 cats can be ordered with some beefy gaskets (I recommend them). I used new OEM Nissan gaskets for the headers. The cats also have long bungs for the O2 sensors so that you do not throw a CE light. Nice feature and I have yet to see a CE light. The only weird thing about the fitment is that the support bracket for the cats from the factory does not mount up to the cats. I talked to the guys at Z1 about this and they have all run without the OEM brace for years without incident.
INSTALLATION: I have access to a lift and air tools which helps a lot. As a result the cats came out pretty easily. I was a bit surprised actually with all the horror stories about demon bolts. The passenger side header is not too bad, but the driver's side takes some time and it seemed easiest to remove the A/C line so be ready to recharge that if you do it that way. Also remember to hook up your vacuum lines. I forgot and the car was idling really rough like it had race cams and I had no power brakes. Whoops!
POWER & SOUND: Nice improvements for both. I just have the butt dyno to go off of, but it definitely is a more noticible improvement in power than the Stillen cat back I did earlier. I believe the claims of 10hp for the cats and 12-14 for the headers. It will be nice to get an intake and a tune later, but for now the car finally feels fast and very responsive. It revs quite a bit quicker too. I am on snow tires now, but I can easily get the traction control kicking on in the first three gears.
Even better is the sound. Along with the Stillen exhaust, the car sounds fantastic! Quiet enough when you need it, but really opens up under load. Everyone said the cats would produce lots of raspy sounds and buzzing when you let off the throttle, but I get none of that when I lift. I hear a little rasp with the windows down at low speeds and high rpms briefly when I accelerate, but that is it. I did not even hear it with the windows up.
OVERALL: Very satisfied with these upgrades and recommend them to anyone. Most people will probably do the cats 1st as it is a lot less labor, but the headers look great, sound awesome, and add noticeable power. I initially wanted to do everything Stillen, but could not justify the additional $$$ for the same performance gains.
Here are the cats waiting to go on the car
Cats do discolor noticibly after a fair amount of driving
Headers still sitting in the box
The headers are tough to see installed, but this is the best angle
Are these touching the steering rack on hard RT turns?
Not that I am aware of at all. I sure don't hear anything.
UPDATE: The headers still look like new and sound great with the cats and Stillen exhaust. However, I think I got the cats hot enough to melt the insides of the one on the right bank. I got a CE light indicating an issue with that cat. I have not had a chance to check the internals yet. I am not sure if that is the case or if it just needs a tune, but I may have turned it into a test pipe with all of the heat.
03-16-2016, 05:14 PM
