I've had these headers installed on my car for almost two months now and I'm finally writing a review on what I think. This will follow the same format as my previous reviews.Keep in mind I had this installed with a Motordyne XYZ Y pipe with a high flow catalytic converter, and Tanabe Medallion exhaust. Performance, installation, and sound may change depending on your setup.
Package: I can't say too much about it as I bought these unused from a seller here in the forums. The box was raggedy, but the headers were wrapped in bubble wrap, instructions were present, and all gaskets/wires, and bolts were there as well.
Installation: I did not install these headers myself. I would not recommend it unless your ready to break tools, bust knuckles and become infuriated over it's difficulty in these cars. My shop misquoted me at $400ish for the headers and exhaust. After the work was done, they say the job cost closer to $600-$800, but they kept their original quote and that's what I paid. The passenger side is easier than the driver side. The driver side is difficult to position, tighten, and work around in every sense of the word. Bolts may break when removing the old header. Good news is that you do not have to play with the demon bolt, just remove header and cat in one piece. Over all, this is probably one of the most difficult installs there is for the Z. There is nothing easy about it. When extending the O2 senors, extend one wire at a time and do not use an impact wrench with them still in the cats. You will destroy them and will need to purchase new ones. Also take note, that I currently have a SES light that has been persistent since the install. I'm hoping tuning will resolve this.
Appearance: I believe these may be mild steel and not T304, but I don't know for sure because I did not order them. If you have a flashlight they look badass. It's difficult to see them as they are tucked deep in the engine compartment and they are coated black. The ceramic coating I believe is good for 1600F and looks awesome. It looks understated for sure. If you want something more flashy, they have different coating options that keep the metal appearance. They
WILL change color due to extreme temps though, so be aware.
Performance & Sound: There are no test pipes, ART pipes, HFC's, or any other pipe that connects to the stock headers or shorty headers that will make as much horsepower as Long Tube Headers. Scavenging is very apparent with the PPE's. Rasp is also very apparent with PPE's. If you are running longer resonators or cats somewhere in your exhaust, it will help
A LOT with reducing or eliminating rasp. These will turn any tame exhaust system into a chest pumping beast. I have these installed with the Motordyne XYZ Y pipe with CAT, and Tanabe exhaust. With these, the exhaust has a very high pitched sound when running over 5k rpm. The sound starts changing after 3500rpm. At redline, the sound is nothing I've heard from any exhaust setup on these vehicles; It wails like a banshee. At low rpm, it has a smooth mellow sound that burbles off throttle. Everyone (even my Mother in Law) thinks the car sounds great. It's very primal sounding. With a full exhaust untuned, I picked up 30whp over my best baseline. Power was still building at 7500 rpm with stock intakes. This still holds true with CAI's as well. It was dynoed a week after baseline in the same conditions and immediately after install. It did feel like the car picked up more power as the ECU adjusted. The car only had about 3k miles at time of baseline and install.
Conclusion: I picked these up for $750 which I consider a great price. Install was $400. For $1150 total, (exhaust install included in price) this was a great bang for buck purchase in my case. The sound is unique, the whp increase was dramatic, and they work as advertised. There was no fluff in the numbers. I made power in every part of the rev range, my low end torque did not drop, but improved, WHP increased everywhere, and they fit perfectly with the Motordyne Y pipe I had installed. The cats and Tanabe exhaust cleaned a lot of the rasp out except when the exhaust is still cold. I would say rasp is the only thing I did not care for. But for the vast performance increase, it is more than worth it. Here is the original dyno chart as well as a couple video's I have in another thread.
Dyno: Blue is baseline, red is LTH, y pipe + cat and exhaust, green is everything in my sig (no M370)