Alright...there seems to have been many many questions about the install of the newer OBX Headers/Y-pipe. So I have decided to do a small writeup on the installation of these headers/y-pipe. So below I have made a faq with some of my answers that should be right but if I am wrong on anything feel free to let me know...and like everything else, this is a guide to help you on your install and any questions you have, so if you screw something up it is not my fault


FAQ

1. Are these worth saving the extra money over the Cattman's?

(Answer) If you are a do-it-yourself kind of person then yes definitely, the Cattman's are an awesome product and have no fitment issues whatsoever (I have owned a set of Gen III's) and the peace of mind is nice, but if you aren't afraid to do some small modifying and saving around $500 sounds good then yes the OBX headers are for you.

2. Do these make decent power compared to the Cattman's?

(Answer) The OBX Headers make just as much power as the Cattman's. Depending on who you ask some will tell you they make more but I think that since the dyno's differ I would say all around they make around the same power.

3. I have heard you have to extend the O2 sensors, is this all 4 or just the primaries?

(Answer) Alright, when I installed my headers all I had to extend was the primaries which are the O2 sensors in the collectors of the headers...now if you choose to plug up the secondary O2's then you might have to extend them, I don't know because I did not hook mine up.

4. Do you have to relocate the rear bung for the primary O2 sensor?

(Answer) Don't know if you absolutely have to but I would 100%...it makes the install a lot easier and you won't be so worried about it hitting the steering rack and whatnot. All you need to do is move the bung 90* to the right on the collector and your good to go, you could have a shop do this for you or for the DIY'r you could do it in your garage (like me...lol)

5. Will I throw a SES with these headers?

(Answer) Yes most likely, since you do not have any precats for the secondaries to monitor you will throw a code which is why it is useless to plug up the secondaries to begin with since they will still throw a code because there are no precats. The SES light thrown will not effect your performance at all because the primaries are the only O2's that affect your A/F ratio. Now all you need is a dual output O2 simulator which you can get from here: http://www.02sim.com/ Some have reported not throwing a SES and most get one. When I installed my Cattman's I threw one upon first startup, with the OBX's I have been driving around for 1 1/2 months now without a simulator and have yet to throw a code, but that's just mine.

6. Should I use the gaskets included with the headers or the OEM ones?

(Answer) Definitely use OEM multi-layer gaskets because the ones included like every other header kit are crap. Now if for whatever reason you have to use them then they are ok but plan on changing them down the road because they won't last as long as your OEM ones.

7. Is there that much modifications to make these work?

(Answer) That depends on who your talking to. I didn't think it was that bad. The only modifications I had to do was to move the rear bung 90* to the right, plug the 2 secondary holes in the y-pipe, trim down the crossmember like 1/2 inch for the flex section, and then grind down the rear motor mount bracket peice for the primary tube on the rear header. That's it. Not bad at all. Some people claimed to have installed them without any modifications but I would plan on doing the above on your install.

8. Do you have to have a lift to install these headers?

(Answer) NO!!!! You can install these with your car on jackstands...I installed both my Cattman and OBX's with the car in my garage on jackstands. Even with the one peice rear header/y-pipe deal it's not that bad. The y-pipe header peice doesn't weigh that much and once you get everything trimmed and out of the way it isn't that hard to put up on the head.


That's all the questions I could think of for now, I am working on the Install Writeup as you are reading this so I will post in a little bit, but I hope this helps out a lot with some of the questions and concerns people are having with these headers.

 

Installation: Now bare with me hear as I installed these quite a while ago, so if I left something out please feel free to let me know because this is going off of memory, I didn't take a gazillion pics either so it will mostly be an overview because I'm assuming you guys can figure out the small details . So use this as a basis to go off of when you are installing your headers, it's not an instruction manual but I'm sure it's a good outline to follow.

Alright first things first. Here is a pic of the bung relocation courtesy of C-Young:



1. Remove your filter, midpipe etc. off of your intake.

2. Proceed to remove your intake manifold (12mm) upper only though.

3. Remove your Radiator fans, only 2 bolts on top (10mm) and 2 on bottom (10mm) unplug them as well.

4. Jack up the car and put on jackstands.



5. Take off the passenger side splash guards.

6.Take off the front heat shield off the header.

7. Undo the 2 front O2 sensors and the rear secondary. 22mm wrench or an adjustable wrench.

8. Unbolt y-pipe completely from the precats and the cat.

9. Unbolt exhaust manifold from head.

10. Drop the front manifold throught the bottom.

NOW THE EASY PARTS OVER....LOL

 

11. Undo the rear O2 sensor off the rear manifold

12. Now it would be easiest to unbolt the precat from the rear manifold but mine decided to be tricky and stripped out so I couldn't undo it so it was a little hard to get to the nuts for the header.

13. Unbolt the rear manifold using a combination of underneath the car and from on top to get to the different nuts.

14. Bolt the front header to the head.

15. Go ahead and test fit the y-pipe/header and see where you'll need to cut (even though you already should know by now...lol)

16. Grind down the crossmember so that it's not touching the flex section.



17. Now grind down the rear motor mount peice on top that's almost just like a cover for the top of the mount, this can be kind of tricky, I've found it to almost be easier to undo the mount from the engine and cradle and take out of the car and since all you are grinding is a plate you can just cut it all the way off...photo courtesy of datdude20.



18. Your header/y-pipe should now slide up into place.

19. Bolt on header to head

20. Bolt y-pipe to cat and to front header.



21. Plug in your O2 sensors. You may need to use some zipties on the front because my wire was being hit by the fan so I ziptied it so it wouldn't hit.

22. Double check and make sure everthing is bolted up tight so you won't have any leaks.

23. Lower car back onto ground.

24. Re-install fans, intake manfold, intake.

25. Enjoy your headers!!!!

 

heck yess!! thannkkk you for taking your time and writing this.. i'm sure this will help many

 

Nice. Thanks!

 

Great Write Up!

What did you use to do the grinding?

 

I have never been a "DIYer" but now... I think i might just give it a try...
TY for posting this

 

Maybe its me, but if I buy something that's meant for my car, I shouldn't have to modify my car for it to fit...

 

^^+1

 

Good for you...if you don't like the OBX headers then don't buy them, as for the pointless post bashing the product, please post in the OBX headers thread, not my install/faq thread.

 

I just had to remove my intake manifold to change my plugs and it took me about 45 mins to an hour just to remove the intake manifold. I heard there is a way where you can rock the motor with the engine mounts out. Anyone do it that way?

 

Did you have some problems with anything??? It only takes me 15-20 minutes tops to remove my intake manifold. It's only 7 bolts/nuts holding it on and a couple vacuum lines??? You must remove it to get clearance to some of the top nuts on the rear manifold. You cannot access these with the upper intake manifold on the car even with the engine rocked back. The first time I installed my Cattman headers I took the crossmember out because I was putting in solid motor mounts and even then I didn't end up rocking the motor to make it easier, you can get to all the nuts on the rear manifold just fine after you remove the intake manifold.

 

Yay

I'm not a 3.5 but this will help a lot! Thanks pimpin!

 

Woah! all that red font makes the regular font look 3-D


Are OBX equal length y pipes?

 

LOL...and to answer your question...essentially yes, they are equal length.

 

One point that you might consider adding if you deem necessary - check for any exhaust leaks and that everything is bolted down properly before reassembling (usually you bolt on everything loosely first, then tighten each piece at a time). I know it is common sense, but many people will be so excited to drive the car that they forget to check for leaks and then have to take everything apart again later if there is a leak.

 

Total cost?

 

I paid $330 shipped for mine.
Gaskets should cost another $20 or so.

 

Headers = $340 shipped
Bung Plug = $3
O2 Sensor Bung = Free at the exhaust shop
O2 Sensor relocation = $25
24 Gauge O2 Sensor Wire for extension = ??? (maybe someone can help with that)
Elbow Grease and Sweat = Also free

$368 total for the headers and install sure beats paying a shop $700 just for the install. That's why I'll be a DIY'er come June 6th... can't wait!!!

 

Added...I have def. done that before on an old Mustang of mine

I just used old O2 sensors off of my old motor for the extension wire. Good luck with the install, just take your time and don't be rushed. And remember, nothing ever goes as smooth as expected so don't give up, there are parts of the install that are very frustrating but overall it's not that bad and once you are done, the first time you drive the car you will be very proud of what you have done.

 

Man... I paid like $380 for mine.

 

i kno i was lookin at prices on ebay and it seem like $380 was the price, man i gotta go back to searchin again

 

yeah the prices went up :| we shoulda jumped on them when it was cheaper!

 

WOW perfect timing. I just ordered mine two days ago. This writeup will come in handy.

Thanks.

 

are you going to DIY? let us know how it goes

 

wow thats awesome. Kinda sucks how cattman monopolized the headers market being the only one producing equal length y pipes; not anymore!

How does it sound? btw thanks for the write up.

 

Well I still have my stock cat/catback so I didn't notice a difference, but with the full exhaust the VQ35's sound pretty sweet!!! I had full exhaust whenever I had my Cattman's on and it sounded decent.

 

Please keep this thread on topic and take your comments to PM or a thread in the appropriate subforums.

 

Thank you...

 

nice writeup

 

Great thread. Anyone know the power gains with this piece and stock cat and catback exhaust?

 

I would say after tuning somewhere between 25-30 hp to the wheels. So it's a pretty big jump. With SSIM/Headers/Y-pipe/Untuned I picked up 7 tenths and 5mph in the 1/4....


And Thanks to everyone for the compliments on my writeup...I really appreciate them.

 

Yeah once I find the time. They should be here by Monday, so probably next Saturday hopefully.

I'm gonna order some OEM manifold gaskets and plug up the rear primary bung(the one that is too close to the steering rack), and move the rear primary o2 sensor to the next bung downstream.

Ill let you guys know how it goes once I finish.

 

Anyone know if we DEK (01) guys willl need to remove the intake manifold to get at the rear exhaust manifold gaskets? What stock gaskets is everyone ordering to replace the OBX ones?

Thanks

 

I got just the OEM multi-layer exhaust manifold gaskets from Dave B at South Point Nissan.

And removing the UIM will help to some extent.

 

Thanks.....wondering if I need a IM gasket after I remove it.?

 

can you pass emissions with the headers?

 

Great write up! Take some videos. I only see videos of 5.5 maximas with either hotshot or cattman. never obx.

 

Question, where/how did you hook your wideband up?

I'm getting ready to put these headers on next week ( ) and I see four bungs.

I'm going to move that one on the rear header 90* like you and C-Young did. Run the rear primary to that one and run the front primary to the other.

I have a dual output O2 sim, so can I just leave the two secondary O2s physically disconnected from the header system? That way I can block off one more bung and hook my wideband upto the other.

 

Well, I installed my headers a week ago and I did it a little differently than most of you guys.


As we all know, the rear primary bung is too close to the steering rack, but I did not get a new bung welded. Instead, I put a 18mm plug in the that bung and I put the rear primary o2 in the next bung downstream.

I extended the o2 wires by using the old secondary o2's wire. I bought some heat-shrink crimp on connectors at radioshack and crimped in the extension wires in between the primary's harness plug and the actual o2.

Since I used the secondaries' wires, I did not have to worry about impedance mismatches and whatnot, and I was also able to use the heat protective tubing that they had.

I did the same for the front primary because it was a tight fit.


For the rear motor mount, some work was required. Instead of grinding where it was touching, I completely removed the thin sheet of metal with an air chisel. It doesn't do anything anyway.


For the secondary o2s' heater circuit, I bought (4) 10watt, 10ohm resistors at radioshack. I wired 2 of them in series and used that to simulate one sensor, then did the same for the other.

I used a dual output sim to simulate the actual o2, and so far so good.

Every once in a while I will get a pending code for the secondary o2s but it never throw a CEL and usually goes away.

But for the heater circuit, it appears that 20ohms works, which is why I wired two 10ohms in series.