I posted this in the performance section but it may not get as much play as here:

Installed my OBX header today with the stock mid pipe. Wrapped it in Thermotec to keep the temps down (you can grab the header briefly while the car is running with no burns). The back primary O2 sensor was a PITA to get in but finally got it up and running. One thing to help with the removal/install is unbolt the exhaust bracket from the bottom of the transmission (2 14MM bolts) this gives a bit more clearance.
The car is definitely louder when you get on it. Sounds more like an Infinity for lack of a better description. Using the trusty old G-tech the 0-60 has improved by .3 seconds and horsepower is up by 5. The power increase is very noticeable in the upper RPM range (4K+) and especially cruising at 65 and nailing it. The motor is running leaner now but I have an SRT intake system on the way so we'll see how that fairs. After the install I reset the ECU and took it for about a 150 mile drive. The mileage has increased by 3 MPG (stock midpipe/CA/exhaust) but long term tests will tell the true tale. After the drive the car has quieted down quite a bit as well. Peak ignition advance is still 39 degrees but it is much higher generally than before the header install. Perhaps reduced detonation has done this. Still building all the data but overall I am happy with the mod for now. Ultimately I will go FI but I just want to see what the 2J can do normally aspirated without getting into the motor itself (head work/cams/etc).

 

Any pics of the installation process? Or any before/after pics? Did you get a CEL after installing the header?

 

DIY header install for GS300 *WITH PICS*
https://www.clublexus.com/forums/per...with-pics.html

 

^^ thanks for the link!

 

Lol @ trusty g-tech. I hope you don't really believe those numbers.

 

I believe that there has been an increase and the numbers are only a reference point.

 

How did you measure for a 3 mpg gain, just wondering. That is an awful lot for headers.

 

I agree that the increase in MPG is very high. Filled up the tank, drove the same route to one of the remote offices that I go to, setting the cruise control at 70MPH. Had something to eat, drove back under the same conditions and then filled up again. Did the math and it came out to an increase of 3.02MPG increase. My Garmin Nuvi with the Eco function showed an increase of just over 4 MPG but I trust that far less. The average engine load was down about 5% and the throttle % was down as well. Long term tests will prove or disprove this.

One or both of the stock cats may have been partially clogged as well. So again, the results are just what I am seeing on my car.

 

do you by any chance have a sound clip of how it sounds with all other components installed?

 

http://www.youtube.com/watch?v=FUyjaZetnk4 ....BAMM well in the bathroom multitasking

 

excellent thanks

 

Dean,

Thorough install review.

 

Just giving an update...
The car has averaged out to a 1.6 MPG increase with the header. I went back a few days ago and re-tightened all of the fasters as the gaskets are compressible. Almost no difference from stock in terms of sound output. The performance is noticeable in the midrange, no downsides performance wise.
Still very happy with the purchase.

I received my SRT Intake from Mo yesterday and installed last night.
The intake and ECU piggyback make a VERY noticeable increase in performance. The car is also louder when under throttle. Idle and cruise remain pretty much the same noise wise. The scanner is showing an average decrease of 4% in engine load for the same driving conditions as before. We'll see what impact this has on mileage. You definitely know that the car is not stock when you get on it now. I have no objection to the noise but some may. The instal was really easy, took less than 1/2 hour to install the intake and ecu. The piggyback, from what I can tell so far, does a good job with fuel management. It leaned out the low load maps (which is a good thing for mileage and should not effect longevity) and has taken care of the leaner condition in the higher rpms/load that was caused partially by the header. The key is in the tuning -- if you are going to run an aftermarket intake on a GS3 you NEED to have a piggyback fuel computer to reap the rewards. I highly recommend the SRT-looks good, easy install, good sound, NOTICEABLE increase in power, no decrease in low level/off-idle performance, and I will advise on the mileage difference after a few weeks of testing.

 

Just for clarity, this is a video of an OBX header with an aftermarket exhaust (Top Speed Pro-1 Exhaust to be exact.) I've searched for years (yes, years) and have yet to find a video of an OBX header with an OEM exhaust.

 

I can get one maybe with my iPhone but there is no difference in sound, at least noticeable difference, with me running the OBX header, stock midpipe and remainder of the exhaust system. In the video you are hearing the Pro-1 exhaust. I've heard a few cars in person with the Pro-1 and it is just a bit too loud at cruise for my tastes (I drive a lot). On a "second car" I would not mind it at all.