I read on How Stuff Works that a free-breathing (aftermarket) exhaust actually helps.

 

Things that will marginally improve gas mileage:

i/h/e
lowering springs for less drag
any kind of body difuser will get you a little less drag also.

I stress that these will only get you marginally better gas mileage.

 

OK -

Technically, anything that makes the car run more efficiently ie: faster and free flowing, will increase gas mileage and performance.

Where you will lose it, is when you force air and fuel levels for power increases - such as FI of any sort, larger injectors, port and polishing, etc.

The general bolt-ons, like Stillen CAI, plenum spacer and a true dual catback, all will increaser efficiency without adding fuel consumption. If you tune the car for better performance, you will LOOSE gas mileage - why? Because these cars run lean, and tuning only richens the mixture for added performance - hence loosing mileage.

The other issue - which is your foot - will be the worse thing of all. After the mods, the car will run better and faster, and you'll constantly be in love with that, hammering the gas pedal to hear it roar and feel it pull.

when I first got my car I averaged 24MPG - after heavy modding - if I drove it NICE, I got 18. Now with the Vortech and tuning, driving NICE gets me about 17-18. But the way I drive the car - it gets about 9 -

 

Dude, you just challenged Brainiac


You're in for it now, homie!!

 

Sure sure like this is the first time.

 

 

:d

 

A turbonator, of course (hope I don't get banned by the gestapo)

 

thanks for all the input guys. I ordered a k&n air filter already and will eventually probably go with a nismo intake. That wont void the warranty right? Also someone mentioned the irridium plugs. When i went to the auto parts store to get some the guy told me that the Z may or may not already come with iridium plugs. Anybody know a definative answer on this? Cuz plugs and better air filter are going to be my first two things i do to my z.

 

My 03 didn't come with Iridium plugs, I bought them on-line and to tell you the truth I haven't really noticed any gains in HP or gas mileage. It may only make a marginal difference at best. Also, don't waste cash on a nismo intake, just get a JWT Popcharger, it only costs about $100.

 

I'm pretty sure the Nismo CAI is considered R-tune which is not covered by warranty.

Exhaust, suspenion, and sways are S-Tune.

 

so are you saying the exhaust wouldn't effect the warranty? because thats a real issue for me until the warranty runs out. I have a 100,000 mile warranty that lasts until 2008

 

Correct. Why would an exhaust cause the motor or drivetrain to break.

 

Go to a 350Z meet and look at the NISMO intake. Its a quality mod.

 

ANYTHING you put on your car that is not factory, the dealer can and will use against you - in your time of need...just remember that!!!

You can always remove simple mods before going to a dealer for such services as well.

Rick

 

this one won't hurt yur gas mileage JATO assist

 

+1

 

Anything that reduces weight especially unsprung weight will not hurt your mpg but are definatly performance mods.