I installed the cheapo DNA Motoring headers on my 01. On the facebook Xterra groups I constantly see people asking questions about them so instead of rewriting replies I wanted to post this to go over the general issues you might find yourself in when installing the headers. This will not be a well constructed tutorial or anything of the sorts. Most of this will be me rambling.
First off the passenger side header, the holes did not line up with the studs, I had to slightly drill out two holes to make it fit.
You will need 3 or 4 new studs for each side, the middle stock ones are to long and wont accommodate the headers. I attempted to use some autozone studs but they were to low quality. I ended up dropping $50 at nissan and getting the stock shorter studs with their respective nuts. These have E-torx on the head of the stud so you can tighten them up completely, unlike the autozone ones that would require gouging the end using pliers to tighten the stud. The stud nissan part number is 14004A, the nut nissan part number is 14004BB.
You will NEED o2 spacers/eliminators(whatever you would like to call them), installed on the bank 2/secondary o2 sensors. If you do not you will get a CEL that is. I bought the 90 degree ones.
Get some metal manifold gaskets instead of the thick ones that come with the header. This is just a recommendation as I have had issues on other vehicles with these thick non metal gaskets leaking. The little flange gaskets I used as I did not believe they would cause any issues, and they did not.
If you have EGR then you are in luck, just hook it up to the header and you are good to go, if not then you will need a block off bolt. Mine came with the headers I bought, however some others did not get so lucky so message them when you go to order them and request you be sent one. I installed some high temp locktight on mine as I do not have EGR.
Many have confirmed these fit N/A and SC models.
When removing the O2 sensor I found the bung on the cat came out with the o2 sensor. I went over to a work bench and found the appropriate size socket and broke it loose from the o2 sensor. This required a lot of struggling, you might find it easier to order new o2 sensors.
You will need to either get a 90 degree o2 simulator on the passenger side header or unbolt the tranny dipstick and zip tie it out of the way. This is because the angle of the bung on the header is faced right into the tranny dipstick, so you wont be able to screw the o2 sensor in. I went with the 90 degree o2 simulator.
I have a 2" body lift and this made the procedure 10x easier, I couldn't imagine doing it at stock height, I actually didn't even remove my wheels as I have 2" spacers and the wheel is very offset so I had a bunch of room to work but you will likely need to remove the wheels.
My original passenger side manifold was cracked all the way through. This isn't a tip, but likely the cause of most peoples exhaust ticks.
I had to remove my front drive shaft to get to all the flange nuts on the driver side, others have said they did not have to. However I did.
The heat shield bolts will break during disassembly. Carry on.
Liberally apply your favorite penetrating oil as a broken exhaust stud ain't nothing to mess with.
Once installed I noticed a HUGE sound increase, everywhere I go people ask if it has a V8. I also have a cold air intake and a flowmaster 40 with 2.5" pipe out, so results may vary. I kept my secondary cats, if you removed them I would assume this would affect the sound dramatically.
I also ended up selling the old cats for $30 to a recycler.
I found to give you the most room go ahead and remove the secondary cats completely while installing the headers.
The headers really opened up my X, I do believe however this is mostly due to the fact my old primary cats were clogged up, however I'm sure the increase in flow helps some. Before this I could not go faster than 60mph on 33s, now I can pass people going 80+.
I will add random pictures of the process shortly and any thing else I think of, I will update the post.
Link to the o2 spacers -
http://www.ebay.com/itm/122006737728
Link to the headers from DNAMOTORING(this is their actual ebay name in case this link ever dies) themselves -
http://www.ebay.com/itm/162168512650
bung after removing off o2 sensor
cracked passenger original manifold
egr bolt
removed driveshaft showing access to flange nuts
comparison between old manifolds and new headers(i dont smoke, and if i did it wouldn't be pallmalls)
driver side comparison
passenger side installed from above
passenger side installed from side, this is before i installed o2 sensor
driver side installed from above
driver side installed from side(before i installed the spacers on secondary o2 sensor)
metal gaskets i used
cat with the missing bung i took with when removing the o2 sensor
eBay/amazon DNA Headers
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