I recently installed Jemini Power Performance headers and a Y-pipe on my 2014 Nissan Maxima engine swap. As Adam mentioned in an earlier post, when it comes to the O2 sensors, here’s what you’ll need:
Two 90° O2 spacers for the downstream sensors
Harness extenders for the upper two sensors (see photos)
For the rear downstream sensor, you’ll need to remove the 90-degree fitting and use only the extension portion—otherwise, the passenger-side CV axle will be in the way.
If you decide to tune your Maxima (which I’ll be doing soon), you’ll probably need harness extenders for the downstream sensors too, once you remove the spacers for the tune.
You can order the o2 extensions via Nisformance here. You need to look at your plug and then check against the type to ensure you get the correct one.
Long-awaited Headers are back for the VQ35 platform for the Nissan Maxima 2009-2024. These are comprised of 304SS and modeled after the OBX versions of prior day. *OFF-ROAD USE ONLY*
These headers are carefully modeled after classic versions from years past, ensuring they’ll clear both the front and rear motor mounts without issue. The quality is a massive step up—about 10 times better than anything previously offered by OBX. They’re a direct fit for my own Y-pipes, and they should also work seamlessly with the Motordyne Y-pipe.
Proven Gains: Thanks to the Community
A huge thank you to Gerson and King Vonn in Texas, who handled the installation and dyno testing. Thanks to their efforts, we have real-world proof of the horsepower and torque gains these headers deliver. Their work has been essential in bringing this product to life for the Maxima community.
Tuning: The Key to Unlocking Performance
For the best results, a tune is highly recommended. Gerson Flores is the go-to expert for Maxima tuning in Texas, both remote and in-person. While you can use O2 spacers, you simply won’t see the full performance benefits without a proper tune.
Pricing, Payments, and Package Deals
The new headers are priced at $599 plus $45 shipping, and each set comes with gaskets for the heads. The price reflects not just higher production and transportation costs, but also the fact that there simply aren’t any other options on the market right now. I want to be clear: this is not about making a quick profit—over $12,000 went into developing these headers for the Maxima community. I did this because I could, and because the need has been there for a long time.
If paying the full amount upfront is difficult, don’t worry—payment plans are available, with no judgment. And if you buy both a Y-pipe and header together, you’ll get the combo for just $1,000 shipped, saving $75.
Thank You to the Maxima Community
Thank you for your patience and support through the development process. The wait is over—let’s make your Maxima perform its best!
Installation by Gerald Johnson (2014 Nissan Maxima)
Introducing Racingline’s new High Flow Pre-Cat exhaust systems for the 2004-2008 Nissan Maxima. Engineered to be a 100% bolt on, these units feature fully metallic core Stainless steel high flow cats that flow more than double that of the OEM units they replace, resulting in 8 HP and 14tq at the wheels.
Price: $499.99 Part Number: HFPC-A34
Designed as a “header alternative” for cars that are experiencing failed pre-cat units. Until now, if a pre-cat failed your only options was customizing a header set (that takes upwards of 8-10 hours installation with no guarantee against SES/CEL lights) or going to the Nissan dealer and spending $700 each on the pre-cat units.
Racingline HFPC’s feature:
100% bolt on performance in under 4-hours
3-way ODBII compliant metallic core substrate units that flows more than double that of the OEM units
No CEL/SES lights.
No modifications
Tig welded 304 stainless steel body’s
8hp & 14l ft/lbs @ the wheels
weigh 10lbs less than the OEM units
Will work with Racingline, OEM and all other Ypipes designed to mimic the stock mounting setup
The exhaust manifold of the TurboWorks company is made of 100% stainless steel.
Guaranteed power increase up to 10%.
When performing engine tuning, the exhaust manifold should be replaced at the very beginning, because the exhaust gases, extruded from the cylinder, are sent to the exhaust manifold, which is part of the engine body, then are directed to the first section of the exhaust pipe, and then to the silencer, or several serial positions mufflers and then to the outlet part of the exhaust pipe.
The set includes a set of gaskets.
Our offer also includes lambda probe adapters that eliminate the catalyst error.
This is another option for buying O2 Simulator. They have been testing and fully working on 2002-2003 5thgen Maximas. Should also work on 2004-2008 6thgen Maximas as well.
The iO2 was originally developed as tool to aid in the diagnosis of catalytic converter and oxygen sensor fault codes.We believe this is the most intelligent oxygen sensor simulator available, that’s why we named it the iO2. The iO2 uses the vehicles live oxygen sensor signal to emulate and output a signal that closely resembles that of a good functioning catalyst.
The desire to simulate an o2 sensor begins with the desire to remove the catalytic converters to allow free’er exhaust flow. The trouble is, the rear o2 monitors the exhaust content and the PCM can determine if the catalyst if performing or not. If the catalyst is removed, the PCM usually starts reporting P0420,p0430 faults for catalyst efficiency.
Simulation approaches in our research showed two basic idea’s, an electronic and a exhaust spacer approach (defoulers)
Electronic Simulators
Let’s start with electronic, the 555 timer. Developed years ago the 555 timer was and still is the electronics hobbyist dream.The 555 timer was setup in such a fashion to simply output 450 mv to keep the PCM thinking the rear o2 was present.
However as PCM’s grew in software function, tests were added to check if the rear o2 was actually able to produce a voltage range of 0-1 volt.Of course, this made the original 555 design obsolete, so the output of the 555 was changed to pulse from 0-1 volt at a fixed or even adjustable rate, this is the most current use of the 555 that we know of.
This does work for older technology, however it is hit or miss or will not work for newer PCM’s. It is a unreliable approach that will more than likely lead to an catalyst efficiency fault at some point.
The resistor capacitor fix….
An very common electronic filter circuit, but does it work?
About as well as the 555, yes and no, its once again hit or miss dependent on the vehicle. It will pass the PCM’s test for o2 sensor activity, just like the 555 timer will, but when it comes time to test for catalyst efficiency (p0420,p0430) that’s when they fall short.
Defoulers….
The direct approach, this seems to be very popular maybe because electronic approaches haven’t been very reliable, and its cheap. Do they work? once again yes, and no. First they are far from from stealthy, secondly they require routine maintenance.
They are not a guarantee for every vehicle, difficult to get just right and require cleaning from time to time
At any rate, we just wanted to provide some insight based on our research.
The io2 IS different.
The io2 itself, is actually a programmed device that reads an actual o2 sensor voltage, then cleans it up.
The software within the io2 will force the output to act as though a catalytic converter is present in the exhaust. So the PCM will see the signal, pass the o2 function test and when it comes time for the dreaded p0420,p0430 the software takes care of that too.
The io2 during testing. The io2 was installed on a 2007 Chrysler product to field test the software. This test vehicle was driven in excess of 850 km’s in all driving conditions, with no P0420 or catalyst efficiency codes generated.
the io2 was installed on bank1, input was taken from the bank1 primary O2, the rear o2 sense wire was cut and spliced to the io2 output.
Question and Answers
Question; What about some other devices on the market for simulating o2 sensors?
Answer; Many devices currently on the market are based on a 555 timer, or a simple low pass filter circuit. Yes they do work, sometimes, sometimes they don’t, they are hit or miss. The iO2 is a programmed microcontroller with software that creates the simulated output voltage, we feel the most reliable approach.
Question; How many iO2’s will I need? some devices can be wired to two o2 sensors at the same time.
Answer; you will need as many io2’s as you have rear oxygen sensors (please see our support page). You cannot reliably use a single simulator for two rear o2 sensors, eventually the engine computer on many vehicles will try to test the function of the rear o2 sensors, it may not test each one at the same time, unlike other simulators,the io2’s software is designed to recognize these tests,so simply put, this will not and cannot work.
Question; Will the iO2 work on my “whatever” vehicle?
Answer, YES! as long as you are using a low band O2 sensor as the input (every vehicle uses a low band for the rear O2 sensor) and the output is simulating a low band O2. This includes all vehicles, even Chrysler,Jeep and Dodge products.
The OBX headers (02-03 Maxima, equal length y-pipe) have been out of stock for at least a year. For engine performance mods I have the Megan OE-RS Catback installed along with berk/Apexi intake and 5 piece spacers. I have compiled all of the information needed to get these headers installed correctly.
My first photo is of new OEM exhaust gaskets. Look at the part numbers and order those if you plan on doing a header install on a 3.5. Although you could get away with reusing the original gaskets, I would recommend spending 35 bucks for peace of mind.
The front (closest to the radiator) header measurements are as follows:
Runner length from where it meets the flange to where all three join cylinder 2= ~10″, 4= ~9″ 6= ~12″
Prices and part numbers:
OEM exhaust header gaskets $13 each 14035-4W015
OEM cat gasket $8 20692-65J00
Spark plug anti-fouler $5 each pack made by HELP 42009, 42002
MAF cleaner $7
Energy Suspension (ES) subframe bushings $25 7.1116G
OBX 02-03 headers $350-380 shipped
The purpose of this thread is to display the newest batch of OBX headers. Exhibit how the install goes and post up some before and after pictures and videos.
Installation Notes
My install went nearly flawlessly minus one heat shield bolt being seized and a secondary o2 sensor not coming out of the old converter. I know these headers are made overseas where quality control is not great. With that being said I think no two sets of headers are exactly the same which means that you may need to trim something during your install. I came to a couple of millimeters from having to trim my front motor mount bracket and my rear bracket went on no problem although it was very close. Probably about 2-3 mm from touching and my front bracket is literally 1mm from touching the header. My flex pipe has about 1/4′ space from touching the subframe.
As you can see one of the primaries comes very very close to the front motor mount bracket but it did not require trimming. Although some may be uncomfortable with how close they are, it is no problem. The mount and header will NOT move even though mine are basically touching it does not matter.
The y-pipe comes about 1/4 of an inch from touching the sub-frame cross member. Again this is not a problem. I have driven it like this enough to not experience any noise and the way I see it the motor really only moves front to back so this tight space does not come into play.
In order for the front primary to have enough wire slack to reach the new header bung, you will have to cut the tape holding the group of wires that travels directly over the middle coil from the larger harness that runs along the top of the valve cover. The tape was holding both harnesses together to about right in the middle of the top middle of the valve cover. Easy fix takes one second.
As you can see below the far left plug has to be unclipped from the coolant pipe in order for that primary to reach.
The rear primary wire has to be extended too. From all of my research people here have been saying to cut the primary either at the wire harness and add some wire to lengthen it or to cut the actual o2 wire and extend those by adding wire. Problem is that it can mess with the voltages. The wire is stainless steel which is nearly impossible for an amateur to solder correctly. My method requires NO WIRE CUTTING!!! You need to remove the wire harness cover pictures below and simply separate the o2 wires from the rest of the wires. First, you need to separate it from the green plug wires, then you need to slit the right side of the main harness that fees into the back of the plastic box. PLEASE TAKE YOUR TIME!!! Be very careful to cut precisely and slowly. Doing this will give you enough slack to reach the rear primary o2 sensor.
This next picture shows exactly where my o2 wire is coming out of the main harness. It is wrapped in a black plastic protector. This picture is taken along the firewall from the driver side, so the top of the picture is the passenger side, the bottom is the driver’s side and as you can see the top left is the upper part of that black wire harness box. The fattest harness coming from the box is what you need to slit the side of and separate the 02 wire from. My o2 wire is running out of that harness down toward the middle of the picture.
The following picture is of one of my secondary sensors. I have the antifouler setup and as of about 75 miles no CEL. This secondary is the one with a green plug and red wire cover. The wire running above it is actually the other secondary which is the blue plug with a white wire cover. Secondaries have different length wires so I recommend this configuration.
Additional Info
As you can now see the y pipe outlet is not quite at 2.5″ but pretty damn close
My new wideband bung on the y-pipe.
The relocated rear header primary bung and plugged original location
Price: $330.00 + Shipping (Add $10.00 for new set of Gaskets) Ordering Info: To order, you can email Adam at SilverSpyder117@Gmail.com
Notes: This will not void any warranty under the Magnuson Moss act. Yes, it deletes the 3rd unmetered cat. No it does not cause any check engine lights or codes. Direct bolt on about 45 min. Install. Yes this will fit 7th and 8th gens alike. This will not fit an Altima SE-R due to the rear header connection only.
About Product & Seller:
Jemini Power Performance was officially founded on 12/28/17 and named after my beautiful wife who God has blessed me with and who puts up with me dedicating my time to this community. This business and group were created for the 7th and 8th generation, Nissan Maxima. We are specializing in bringing back the well sought after performance y-pipe for the VQ35.
We took the Racingline y-pipe and revamped it to a whole new level. Racingline used bare materials such as mild steel, mild coated with aluminum, and 201 stainless steel to produce the initial y-pipe. We had it tested to see these results. Many people have seen the results of this down the road with rust and premature failure.
What we are now bringing to the Maxima community is far better. Top-quality 304 stainless steel construction throughout that will not rust, all custom made gaskets for 2 entry and 1 exit path, shortened .5 inches to meet OEM specifications and a 2 year warranty.
Everyone knows what these y-pipes do and are capable of. If you have questions please ask. From my own experience, I felt a difference immediately after install. Much smoother powerband from the CVT, no lag at all, and steady pickup. From 0 much more responsive and carries that power to well over 100+.
The io2 during testing. The io2 was installed on a 2007 Chrysler product to field test the software. This test vehicle was driven in excess of 850 km’s in all driving conditions, with no P0420 or catalyst efficiency codes generated.
