I am thinking of doing 4.10 gears for my first performance mod and I was curious if a tune would be needed or not? Because if it is then a tuner will be my first mod. I hear that 4.10's are fun.

 

Yes you will need a tune to recalibrate the speedometer.

 

From what I understand You must get a tune if you change gears. Rear end gear changes make rate of acceleration changes that can affect air fuel ratio, not to mention impacting your speedometer and odometer.

 

You are correct. When I first put my 4.10s gears in I didn't reflash the PCM for the new gears. Vehicle went into Fail Safe Mode as soon as I drove the vehicle.

 

u need a retune for the speedo and odo. the person sayin his went into failsafe mode is a rare exception and i wouldn doubt it was because the intaller disconnected some wire somewhere in the installation ( ). gears will make such a small effect on a/f ratios that it is really a moot point. then again, ur gonna want to get a predator or xcal v2 anyway, so might as well and fix ur speedo while ur at it

 

A tune should not be required for gear change, only flash for speedo re-calibration.

 

You're correct on both counts. I've got FRPP 4.10's and I love them for the throttle responce you get in the twisties. Everyone here speaks of acceleration only but this 05 GT will kill most cars in the curves because you can hang the hiney out and throttle steer just like the old 68 GTO I had. 4.10's are a blast all the way around.