This post is a little late, but I've installed the infamous OBX 3.5 Headers on my car.
I do not have that many pictures, but here is a quick overview of the installation process, I will not go into gross detail, because the swap happened awhile ago.
Here is a quick overview on how to install/remove any type of header/manifold from most Maximas (95-03 for sure, 04+ guys this gives you an idea).
Installation (Sort of in order)
-Put the front end of the car on stands-Remove Upper Intake Manifold
-Remove 02 Sensors
-Drop the Y-pipe
-Work on the front collector (6 bolts)
-Begin to unbolt the rear manifold (if you're really pro you can do all 6 bolts)
-Get the jack and support the engine/tranny
-Drop the crossmember
-Remove the rear mount thingy (4 bolts on the motor, it's what the rear mount attaches to)
-Drop the rear header
-Install OBX headers
-Delete EGR
Reverse process, starting w/ the rear mount thingy.
Video on Removing the Rear Manifold:
Problems/Things to know...
-There will be an EGR delete during this process, I'm still working a way around this so I won't have a CEL-Two M18x1.5 bolts will be required (unless you're running a wideband and want to plug it into the headers) to block off the extra O2 ports.
-You can not put the rear o2 sensor on the rear collector, the steering rack is in the way, I used one on the front bank and one near the oil pan, use the screws on the rear collecter and the other o2 port near the oil pan.
-I had to extend the O2 sensor wires for it to reach the location pictured below.
-Get OEM nissan gaskets, atleast the O shaped one, people suggest re-using the old header gasket on your car, they say it's a superior design, I am using the OBX manifold gaskets and so far no problems, but if you really want to go the extra mile, order some new nissan manifold gaskets and O gaskets (remember you're still saving hundreds of dollars compared to cattman, so put that money to good use).
-The flexpipe on these headers aren't the world's toughest thing, sure you can install it out the box, but later down the line it will fail (Me from being lowered, bottoming out a lot), and I hear about other failures occuring because of how thin the inside wall is, so expect to replace the flexpipe on these a year or two down the road, the last two videos below will give a good inside + outside sound of a leaking flexpipe.
-You SHOULD grind off the lip of the crossmember, it's not necessary, but it prolonges the life of your flexpipe and kills down on cabin rattles.
-You SHOULD fabricate your own exhaust hanger after the flexpipe because the OBX's have none. Again, not necessary, but a good idea.
Onto the media/fun stuff....
Below are my collection of photos featuring the OBX 02-03 Headers and some comparison shots and what not....
OBX Headers (Top)
Stillen Y-pipe + OEM Rear manifold (Bottom)
OBX (Left)
Stillen Y + OEM Mani (Right)
These are not the correct ports to block off for a 4th gen, but this is just to give you an idea of what the bolts I used look like (Brought them form Home Depot)
This is where the Bank 1 O2 sensor should go on 95-00 (99-00 fed specs only) Maximas. You will have to extend the wire to get it here.
Drive around with your max like this, you will OWN THE ROAD (it is scary loud, see vid below).
Leaking Flex Pipe (Outside)
:Leaking Flex Pipe (Inside)
For more exhaust clips and videos check out my youtube (username dj_airman)
