The first thing I’d do to improve gas mileage is to add a k&n intake (around 280). This was the first mod I ever did, and not only did I notice a significant improvement in power but I gained about one mpg. My next mod was to add a magnaflow catback exhaust(680, but you can find cheaper), along with a res delete(30) and a Hogan high flow cat(300). I choose this catback because it is the least restrictive of all the exhausts. I then added a TBS(100) and a poly motor mount(50). The TBS helped ever so slightly, but not worth the money, the motor mount however was well worth the money. I then bought an HP tuner(500) and did a little tuning on my own until I got it professional tuned (500). That was worth the money. Soon after however my blue car was totaled.

On my new black car I have all these mods but also decided to get the intake and tb ported for 300 (will cost 400 now). The power increase from this was really noticed in the mid to high rpm, it made a huge difference there. I was told that our intakes are horribly restrictive , so I would suggest getting this done. And by the way, DO NOT USE THE TBS UNLESS YOU GET It PORTED, he told me that it was restricting a lot of air and he knew it wasn’t made for my car, he ported the crap out of it to make it work right. I invested in an aluminum transmission pan(200) to keep the tranny cooler, it does keep it cooler but some might feel this mod to be a waste because our trannys are more likely to break rather than overheat, but I felt it was useful. I also added the zzp shift kit (30) to help out on this as well. It was well worth the money.

My next mod was a QTP cutout(130), which I got mainly because of how it makes the car sound. I had a shop put it on right before the high flow cat, as to get maximum power out of it. My next three mods are debatable as to there effectiveness but I will give you my opinion. The JET mass air flow sensor (300)I added did give me greater power in the higher RPM’s with a slight loss in lower torque, I don’t think it really improved gas mileage but I feel it was a worthy mod. I also added pulstar spark plugs in an effort to gain mileage. I didn’t notice a power increase but perhaps it did increase mileage slightly. At 25 dollars apiece for these plugs I’d say save your money. My newest mod, Fitch fuel catalyst(200), does however offer some gas savings. I’ve noticed perhaps ½ mpg increase, but the gains won’t reach their peak until 1000 miles have been put on it. I would however suggest this mod for someone who’s throwing a code on their high flow cat, because after putting it on, it stopped throwing the code, so it does decrease emissions. In the near future I plan on getting 1.8 roller rockers, pushrods, springs, tranny cooler and a new dyno tune along with a possible set of custom headers. If you have any other questions just let me know.

 

So what is your average fuel consumption around town and highway?

 

average I get about 20-21, around town I get 18-19 and on the highway I get 29-30, my blue car got better but I believe I recently lowered my gas mileage with some tuning I did so I'll look into that

 

So really you got just about nothing in the city, but quite a bit on the highway for a whole lot of money. Your MC is lighter than my Impala. I have a K&N and Magnaflow, and average roughly 19-20 for pure in-town driving, all sub 45 mph, car states average at 30mph. I don't baby it either. Highway I am only getting about 25-26 so you have got me there, but I can buy a lot of gallons for a few hundred bucks. Not to rain on your parade, but I am unsure what you have got for all the money you spent.

 

I get 12-14 in pure in town driving and about 25 highway, that's completely stock.

 

when modding the car I was going for power not gas mileage, but I made sure not to do anything that took away from gas mileage, and like I said, my blue car got much better mileage then this car, I haven't had this car that long and I believe some recent tuning I did makes me waste more gas....and not only did I get better mileage but she also has about 380 at the crank, and when I'm done she'll have over 400, and it won't cost me any mileage

 

I recently added a Jet MAF, K&N CAI, and TBS to my '06 GP GXP. My Gas Mileage went from 22 MPG average to 17 MPG average. I'm going to install MagnaFlow CAt Back system either this week or next week. What can I do to improve my MPG?

 

get rid of the tbs unless you have it ported, it's not made for our cars and restricts too much airflow

 

Are you match porting the Flanges or are you porting the the entire runners as well? What exactly are you doing to your TB and manifold?

 

I don't know.....the guy ported my intake and my tb...I left my tbs on there and he ported the hell out of that as to not restrict airflow coming out of the tb

 

Can you help me understand the 380, soon to be 400 at the crank. I am not seeing a lot of power adders. Figure they are right with the 303 at the crank. Best case I am seeing about 330-340 with what you listed. Maybe I am missing something.

 

maybe you should take a look at my sig

 

when I got my resonator takin off, my gas milage was 7.9 city now it 12.1

 

Why am I getting such poor gas mileage now? Help me out here. You've been at this for a while and I only had the car for two weeks. Help me out. I need a lot of love right now.

 

if I were you I'd take the jet MAF off and put the stock one back one, also you might try putting the screen on the jet MAF that came with the stock one, this screen is supposed to even out air flow, also that TBS might be hurting you more then helping you, mine was ported an inch all round to make it not restrict airflow

 

Man, how do you get this gas mileage? Mine gets.. god, tops it gets 16.2 mpg. City and Highway combined. Driving CAREFUL. Only mods are axle-back and res-delete.

 

Now, you're talking. You must have been reading my mind. This is what I planned on doing. I know for a fact that the MAF is what's hurting my mileage. It's the only thing that can be hurting my fuel economy like that. I knew about the screen already and that's a done deal. The Jet MAF might get shelved until I get a 'HPTuner' to dial everything in later. Especially after future mods like the 'Hogan 3" DP'. Engine might run too lean for the computer limits. Don't want to code.

Well, I had the car for three weeks this upcoming Thursday. I've, thus far, put on a K&N CAI, Jet MAF, and AiRaid TBS to go along with the window tint (20% fw/15% bw) I installed immediately upon purchasing the car. The plan is to add the quick lift rocker arms, port the intack and TB, add a poly mount, Inferno Hood and Spoiler, custom built speaker system by yours truly, plus many more goodies.

It got to be Street/Strip for me, "Show with the Go", but I do want to drive it daily without having to stop at every gas station I see. I'll keep you posted on my exploits and you know good and well that I'll have MORE questions for ya.

Semper91-RS:
Before I made my mods I was getting 26 MPG highway and 18 MPG city. I want to get that back or more. I'm determined to get that back with even more performance. Stay tuned.

 

I did, that is where I am confused. I see nothing that is a big power adder. All little stuff, 5 or 10 here or there. I am trying to see where you gained that much juice.

 

so you think porting the intake manifold is not a big power adder huh? and I guess getting it dyno tuned isnt a big power adder either

 

Sure it can on a typically laid out small block, but after seeing the insides of these motors and the restriction points in the intake and throttle body I just don't see a real huge gain. On my old 69 and 70 4 bolt engines I was able to crank out another 100 horsepower, but it took new valves, springs, cam, lifters, a high rise intake. And surely anyone understands that after making mods like yours you can crank another 10 horse or so out with the right tune. I just don't see enough to add 80-100 hp. Maybe it's just me. . .. Am I alone here????