I have an 03 six-speed sedan and I have modified the intake side of engine with the following mods and results (the exhaust is all stock, for now).

Kinetix intake plenum, Z-tube, NISMO air cleaner with air box mods (holes drilled in the front). Prior to doing any modifications, I made four runs at Firebird Int. Raceway in Phoenix, Arizona. My average MPH for the four runs was 92.15 MPH and my average ET for the four runs was 15.296.

I returned to Firebird last night with the the intake mods and again made four runs. My average MPH for the four runs was 94.50 MPH (an increase of 2.35 MPH) and my average ET was 15.113 (a decrease of 0.184 seconds). For the record, my average sixty-foot times were identical at 2.32 seconds.

Using a horsepower calculator and an assumed vehicle weight (with driver) of 3,600 pounds, my estimated stock rear-wheel horsepower was 220. After the mods with an increase of 2.35 MPH my assumed horsepower is now 237--an increase of 17 rear-wheel horsepower. Because I do not know the exact weight of the vehicle, what is most important to me is the difference between the two horsepower numbers.

It is interesting to note that on my last two runs, I lined up against a stock G35 six-speed coupe and our MPH were virtually the same. I won both races only because I had the better holeshot.

Cost of the modifications: Plenum, $400; Z-tube, $75; NISMO air cleaner, $80; air box mod $0 (as long as you have a drill).

DIY: Yes
Dificulty: Easy
Time: About 1.5 hours
Overall Value: 4 out of 5
Reviews: Good power increase, and as long as I keep my foot out of it, improved gas mileage. Nice intake rumble under hard acceleration. I should see added benefit with these mods after I do the exhaust and the ECU.

Tom

 

did this affect your warranty?

 

only if MAF fails.... and even then.... itd prolly not affect it

2004 Black on Black g coupe 6spd.... aluminum pedals, clear corners, z tube, and pop charger. soon to have 19" volk gt-c's and PIAA xtreme whites in the clearance and corners
Houston Texas

 

damn buddy..with those mods..u should be in the high 13s atleast

 

which plenum did you get?

Did you install the plenum yourself?

 

I agree but he's in AZ. The climate can make a big difference.

 

Air temp, barrometric pressure, humidity, elevation, track, traction, driver, all add variables to the equation.

I'd say you did well with what you have in less than optimum conditions.
Now that you've improved the intake, it's time to improve the exhaust.

You could very well turn in the 14's easily at a different track or even on a different day.

 

How does azcougarman have a 6mt? I thought sedans were only available with 6mt in 04.

The better times could be the difference in what the weathers conditions were for each time he ran. I noticed he ran the after mods runs at night, which could have given him better numbers. Just a thought

 

yea the times are discouraging in the desert. i ran my car at the track (5at) and my buddy came along who has a 350z (6mt) and we were consistenly both running 15.3-15.5 all night. We were really bummed about our results and we were both like "I thought my car would be faster than this." Track conditions were horrible tho. 93 degrees, humid as hell, and im sure the altitude plays a big factor. I beat my friends 6mt every race we had that night too

 

Here is what has transpired since my last post in October. I went back out to the drag strip on November 5th with the same mods as previously mentioned except that I removed the cats and installed test pipes (the rest of the exhaust system was still stock). Keep in mind that the temperature on this night was 75 degrees, as compared to 92 degrees in October. My best run of the night was 14.38 at 98.32 MPH. On this run I had an exceptional 60 foot time. The average time for the other three runs, which had my typical 60 foot times was 14.63 at 98.14 MPH.

I then reinstalled the cats and installed a Stillen cat-back exuast system and went back out to the drag strip on December 3rd. the temperature on this night was 62 degrees. My best run of the night was 14.90 at 95.77 MPH. Please keep in mind that I had traction problems, as the "slip light" was on all the way through first and part of second gear. This was with 25 PSI in the rear tires.

Here is my impression of the stock exhaust system (with test pipes) as compared to the Stillen cat-back exhaust system. With the cats removed I lost a lot of low and mid range torque but the car pulled very strong at and near redline. With the Stillen cat-back system (with the cats installed), it does not pull as strong near redline but the low and midrange torque is vastly improved. The rear end breaks loose very easily now. The driveability factor (or fun factor) is sooo much better. What is interesting to note is that my 1/8 mile MPH (Stillen cat-back versus test pipes) is identical, even though my average 1/4 mile MPH was off by 2.74 MPH.

Yes, I do plan on taking the car back to the drag strip with the cats removed just to see how fast I can go with a wide open exhaust system. I will be doing this sometime in January.

Please feel free to comment.

Tom

 

My car is actually a 2003.5, which is when the six-speed manual was available.

 

Thanks for the detailed results. I'm thinking about putting the Stillen cat back on here soon so it's good to see that there will be a difference. Any recommendations about the install or who to purchase the cat back from? Thanks

 

Grubbs had the best price and free shipping to boot ($883 I believe). As for the install I did it myself--literally. It took about 1.5 hours to install--having another set of hands would have shaved a half hour off of the install time. the car is louder now but I love the sound.

 

Any pics of your modified intake?