GIVE EM' THE BIRD

iTrader: (1)

Alright, heres the scenario; 99M6 SLP SS. 59,xxx miles. Pro 5.0 shifter, SLP lid/exhaust, with torque thrust 2's and 275/40/17 g-forces.

I wanna use this car as a reliable DD. Im sure I will "play" in it occassionally, but mostly i want to drive it so I would like to do some light modding that would be beneficial to both HP and efficiency.

I would like some help from you guys who have actually payed attention to gas mileage as you modded your cars...

At most for now, the mods I'm thinking would be this...

Cheapie ebay Long tubes(210$ after shipping+ 02 extenders)
Either a custom, or TSP Xpipe setup with bullets(about 400 either way)
Ls6 Intake
Ported TB
Descreened MAF

And after all of that, a tune of course

So does that sound like a sound plan for a quicker SS, while retaining good gas mileage and driveability???

Im mainly wondering about the Headers and intake as to whether or not that will kill my gas mileage under normal driving conditions(low rpm, babying the car).

Thanks for the help guys. As you can see I've been a member here for a while but have been out of the loop for a few years now due to going to college for Mecanical Engineering. I'm trying to get back in with this car, but for now I'd like to retain the mild mannered DD attitude with it, in hopes of making it a bit faster under WOT

I am not looking for a certain HP number or track time either, just trying to get a plan developed first and get this car where I feel like its running at its most optimal for a DD

IWGF

iTrader: (6)

I DD'd my 2000 M6 for a while for ***** and giggles, w/ full bolt ons, no tune, I was getting like 25mpg highway. Now that I'm H/C/N2O w/ a tune of course, I get like 28mpg highway.

LS1WS6dreamer

iTrader: (1)

I DD my car. I don't have a lot of mods, but I get around 24mpg doing mostly city driving.

I would prolly pass on the descreening MAFS mod.

I didn't really notice a big difference with my lid, but when I put my P&P TB on with the lid. It was like they were made for each other.

I wouldn't think a LS6 intake would do anything to fuel mileage. I guess if you put LT's and had 02 sensors screwing up that could hurt it. Some people run into that problem with LT's(O2's messing up & codes being thrown).

GIVE EM' THE BIRD

iTrader: (1)

Interesting. Seems like gas mileage would go down quite a bit with a h/c setup. Considering the engine is allowing more air flow which means more fuel flow obviously.

Thanks for the response

IWGF

iTrader: (6)

It's all in the tune mang. I don't really care about the mpg anymore though, usually when she's out these days, it's for trouble

GIVE EM' THE BIRD

iTrader: (1)

I feel ya there. Once I get done with school it will be the toy

black_99/SS

I daily my 2000 M6 with 230/230 cam, ported fast 92 and ported heads. Have long tubes and all and tuned, still gettin 27mpg. Thats the beauty of these cars. lol

darkvader0

I daily drive my 99 TA M6. Daily commute to weekend 500 trips, to periodic 5000 mile road trips. Pretty stock for now. I plan to install LTs and get a 224/224 cam. That's as far as I will go.

My "biggest" mod. is my 4.10 gears. I really, really like them for fun-factor and driveability. I DID notice a decrease in MPG... although they are still new and I am getting on my car A LOT more than I have. I got 19.x MPG on the last tank lol. Everything I read said no loss in MPG, so I might be a dif. case. Plus you can do things like cruise on a surface street at 45MPH in 6th. Even slight acceleration if you need it without lugging.

thegodfather899

iTrader: (1)

the 98 is my DD with some mild mods and i get about 19 MPGs.

GIVE EM' THE BIRD

iTrader: (1)

I know gears will kick the gas mileage down for sure. There is no wondering on that one haha. The only time gears will help gas mileage are on take off/accerleration, but once cruising you are gonna see lower numbers... At 65mph my last m6 was running about 1500 rpms. If I would've gotten 4.10's that rpm wouldve went up a considerable amount, which obviously means that the car is burning more gas with an even load.