I hope i never have to replace headers on any vehicle again! It turned out that both of my OEM manifolds were cracked, so i needed to do this anyhow.
I installed the DT headers and a Nismo catback, i finished it last night. The SES light came on, but I am assuming that is due to the elimination of the primary cats. I'll get the code pulled today. It runs and sounds great! I'll post sound clips soon. There is no degradation of performance from the s/c, before i had only 2 lbs of boost max, it seems to be back to normal now.
To everyone worried about the backpressure issues, can a more open header really be that less restrictive than a manifold that is almost cracked in half?
Anyhow, I just wanted to post that it does work, and i will never do it again. It's not that hard, but it is a PITA to get in there, there is no room.
A few notes:
The Driver side comes with 2 02 mounting locations, but the secondary cat has the factory location of the second o2, so i just plugged the second opening in the header.
jack up the truck, i dont have a lift, but i jacked up the front and took off the front wheels. When you remove the rubber fender liners, you can get to 90% of the bolts you need.
You can only reuse half of the factory studs. The OEM manifolds use 3 short and 3 long studs into the block, the long ones are too long, so we bought 6 more short from a nissan dealer for about $2 each.
There are 2-3 bolts on each side that are impossible to get a socket on the DT headers, the pipe goes directly in front of the mounting hole and the stud is just long enough to block getting a socket on them, unless i missed something.
Other than that, it went ok, just took forever. I didn't worry about a how-to because i was following other people's how-tos and it was pretty much the same. I did pull and install most of the parts through the wheel well rather than through the engine bay though.
Yes a performance header is MUCH less restrictive than factory headers. With most factory manifolds, the exhaust has to "share" the path of escape which inhibits the maximum power it can achieve. The first cylinder pushes out the exhaust on it's exhaust stroke which means that the 2nd cylinder has to push out the exhaust from its cylinder along with the exhaust from the 1st cylinder and so on and so on with the following cylinder(s). With performance headers, each cylinder has it's own dedicated "escape" and eliminates back pressure from the manifold.
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Tim... 2000 Xterra SE 4x4
Mods: K&N Air Filter, AC PML, 17" Pro Comp Wheels, 33" Wild Country MTX, Custom Rear Bumper w/Tire Carrier, 2 inch BL, Hella 500FF's, AC Prerunner bumper, Xoskel light bar with 4 KC Daylighters, AC's IAB, Rancho RS5000 Shocks. Official Build Thread
I'm in the process of writing up a DIY for AC header installation and I see that you had basically all the same issues and the install seems to be similar. Justageorgiaguy Do you have a 2" BL?
I'm in the process of writing up a DIY for AC header installation and I see that you had basically all the same issues and the install seems to be similar. Justageorgiaguy Do you have a 2" BL?
Just by looking at the truck/steering shaft i'd say no...
no, suspension is stock, unless the 4wd is any higher than 2wd.
after driving about 100 miles, i'll be installing some dynamat or something in the cabin. There is a drone from the nismo around 2500 rpms, not deafening but it wears on you. Performance wise, it responds nice, but since the SES code is thrown, the s/c is being bypassed again, so i don't have the full effect.
edit: one other thing i noticed but didnt really cause any issues was on the passenger side header, the rear flange (closest to the cab) is opposite from the stock manifold. It doesn't cause any issues, the gasket is square on that end and can accept bolts in any corner. Not sure why it is different, but I did notice it. I believe the driver side matched up with the stock studs.
no, suspension is stock, unless the 4wd is any higher than 2wd.
after driving about 100 miles, i'll be installing some dynamat or something in the cabin. There is a drone from the nismo around 2500 rpms, not deafening but it wears on you. Performance wise, it responds nice, but since the SES code is thrown, the s/c is being bypassed again, so i don't have the full effect.
Yeah the 2" body lift makes all the difference in the world, much easier to get at every thing.
I have the Nismo cat back as well and I agree that between 2500 to 3000 rpm the drone can be annoying. My muffler may be going bye bye, but I want to get the larger down tubes fabbed up before I do that. I have a theory that the larger down tubes may help to bring the drone back down to the sound levels they were at before the headers.
My guess is the code will be an O2 sensor being caused by the elimination of the cats. Did you install any CEL's?
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DT Headers on '03 S/C - DONE & FINALLY W/ SOUND CLIP!
Linear Mode
