4.10's on an automatic

fireguy266 said:

I have an '03 3.8 six cyl. 'stang. automatic trans. What will happen if I change the stock rear to 4.10's? Will I feel a lot more pep on the street? Will the trans shifting be screwed up? I know the gas mileage will be reduced. Will the car have a hard time on the highway even in overdrive? Any insight on the subject will help. Thanks!

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I have a 98 v6 auto. I swapped the 2.73 gears for 3.73, had to be the best thing I could have done as in the terms of bolt ons. I believe 4.10s will be a little steep on the highway. I turn about 2600 rpms @ 75mph. with 4.10s you will probably be around 28-2900 rpms. As far as gas mileage goes, I went from a smooth 30-31 to 25-26. The drop in mileage verses the perfromance improvement is worth it. During normal driving the transmission is looking to shift into second gear quicker than stock. The`shifts are firmer. Hope this helps.