Need Advice on Rear End Gears

Roger Dixon

New Member
Dec 30, 2018
North Carolina
I currently have a 2001 GT, Vortech v2 with intercooler, Kooks lt headers with catted x pipe and magnaflow catbacks. I'm making 380 rwhp. My tuner suggested going with lower gears to "wake up the car" and make up for some of the torque I lost when installing the headers and intercooler. I dropped about 2 lbs of boost and am now at 8.5 lbs. It is only in the higher rpm's that I feel my car really take off now. I currently have stock rear end, 3.27 gears. I am thinking of moving up to 3.73. Right now I am running Michelin Pilot Sport A/S 3+ 285/40zr18's on the rear. I get great traction and never worry about excessive spinning when flooring it. Will 3.73 gears create excessive loss of traction, and will I still have any functionality in first and second gears?

Thanks for any advice.
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10 Year Member
Apr 27, 2008
Probably cheaper to drop one pulley size and see if that is the pep you were looking for.

Stock block can take a pulley size drop.

If that is not enough pep than look at your long term goals and determine what gear lines up best with the 1/4 mile trap speed you are looking for at the top of 4th.

4th gear engine RPM (3.27/3.73/4.10) @ MPH
50 - 2204/2514/2764
60 - 2645/3017/3317
70 - 3086/3520/3869
80 - 3527/4023/4422
90 - 3968/4526/4975
100 - 4409/5029/5528
110 - 4849/5532/6080*
120 - 5290/6035*/6634*

3.73’s are the most I would go for your power level with a stock tire height.... you will be right on the edge of running out of gear. Personally I still have the stock gears because I spend the vast majority of my time on the street and I am planning for more power. :nice:
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