986 Forum - The Community for Porsche Boxster & Cayman Owners - NHP headers

So I've been looking for high flow cat headers for a while and bought the used NHP 200 cell cat headers from rfuerst911sc (thanks!) to replace my restrictive stock headers.

I installed them yesterday and wow:D

My exhaust setup now consists of NHP 200 cell cat headers, circuit works secondary bypass pipes and a Borla muffler.

Here's how I they started:

http://986forum.com/forums/uploads02...1524147336.jpg

There was obviously quite a bit of corrosion and tarnish, so I started off with using a SS wire brush on my electric drill, then I cleaned them with CLR to remove the rust. Here's the left side compare to the right side after wire brush:

http://986forum.com/forums/uploads02...1524147511.jpg

Then I wet sanded using WD40 using progressivley finer grit aluminum oxide sand paper, from 220 to 1,200. After wet sanding, I would spray down with some Meguiars Ultimate Wheel Cleaner and wipe off with a damp microfiber rag. Then, for the final cycle, I wet sanded with the Wheel cleaner (using rubber gloves!). This cleaner contains some acid (hydrochloric I believe) and does a decent job at removing light corrosion and stains, but elbow grease is what is still needed.

Here's how it looked at the end:

http://986forum.com/forums/uploads02...1524147923.jpg

A few notes:

I tried various products and techniques. The baking soda and lemon juice home made paste can work ok only if the corrosion if very superficial since it contains nitric acid. I tried this and there was not much improvement. Also, as an alternative to SS wire brush, I found that power wet sanding with a rotary sanding flapper wheel work very well for removing heavy oxide and tarnish.

I realize the headers are not mirror polished like new, but for me this was an acceptable finish. When I get a chance, I'll take pictures of the install. In the meantime, I went for nice spirited drive last night and noticed a noticeable increase in torque over the entire RPM band, but even more at the high end. The noise level is just a tad higher than with the factory headers, still has the burble, zero drone, and when you apply WOT, it is music to the ears! Some say it sounds like a GT3, and I do concur with that opinion. I also did not get any CEL codes and the Long Term Fuel Trims now are at about 2.0%. I just hope that I can pass the 94 DB noise limit at AMP next month:dance:

Edit: LTFTs are now in the 3% to 7%, so that looks good. These headers are definitely louder, but I love the sound...