Is it a free calibration? Most importantly would they void out any warranty on the car after going such a mod?

 

With 3.73 gears I get an honest 28mpg if I keep the car under 75 mph. In mixed driving I see between 23-25mpg. I can do much worse but that is when I'm really having fun. Which will be your problem too. 3.73s are probably the single best mod for this car short of FI. If you have an automatic, you may want to consider 4.10s but your MPGs will probably be south of 25mpgs.

 

i thought longer gears increase city mpg? correct me if im wrong

 

They do. 2.73 is considered a long gear even though the number is low. 3.73 would a low gear.

 

you're correct, but this works backwards, 2.73 gears have longer gears than 3.73, the car accelerates much faster with 3.73 because the gears are much shorter hence losing out on top speed as well, so cruising at 70mph on 3.73 will be a higher rpm than 2.73 hence loss in MPGs.

I get 24.5 mpgs cruising at 80-90 mph with 3.31s, 26+ at 60-70.

 

One more question. Is it mandatory to tune the car when swapping gears?

 

No. My dealer that i paid to install my 3.73 gears offered to change my computer for $50 (so the speedometer would be right). I told them no, because i have a SCT tuner and can change things like that myself .

 

Beyond the speedometer issue, your odometer will also be clicking off miles faster. So not necessary for the operation of the car, but not recommended.

 

Well I do plan on ordering the Bama tunes this month so ill have a tuner handy. Another thing I'm noticing is that the rear diff is said to be different than the other years in that a new bearing set is needed when installing new gears. I got a set of 3.31s. Dad forgot he had his 07 GT 500 gears removed when he got it Super Snaked. So I'm going to use those.

 

Theoretical top speed for a 3.73 geared v6 is over 200mph. The car can't even go that fast due to drag and power limitations. The fastest I have read anyone taking a 3.7l was just over 160mph in Germany.

 

Thats still pretty quick

 

This is true. Our top speed is drag and power limited.