Mishri

it depends on the size of your wheels/tires though for your rpm at each speed.. that'll change things. with 4.10s i went from 15mph city to 19mpg city, down from 25 hwy to 22hwy.

08VaprGT

I will check into it and verify once I get back out on the highway. I honestly don't think it was that high. I have 285/40/18's on the rear. The tach might be off a little too. I know that is an issue with these cars.
My car is a 5-speed and came factory with 3.31s so it was a huge difference. I think that in the 07-up cars, 3.31s were factory even with the 5-speed. I may be wrong though?

08VaprGT

Ok, did a little more research. The later model TR-3650's had a .62 5th gear versus the .68 in the earlier GT's. According to the numers, I have a tire that is 26.9" tall, 4.10 axle ratio, and a .62 5th gear. Add this all together and you get 69.25 mph at 2200 rpm. Like I said originally.

mayo

Congrad's on the new gear bro! That's whats up next for me this summer. Since you didn't put up a pic for us pic-ho's, I thought I would come in with an assist

08VaprGT

Thanks Mayo. You won't be dissapointed. The assist is appreciated! Gotta keep the pic-ho's happy....lol

09cs

I believe it was 3.31's and 3.55's as an option. Check the sticker on your differential cover.

gman73

05-06 manual Mustang GT came standard with 3.55 and autos came with 3.31. 07-09 came standard with 3.31 and 3.55s were an option with the manual.

808muscle

School me fellas! Lol

Is it the new fiveOH you can get 3.73's with?

09cs

Lol. Yes 2011/12 has the 3.73 option.

Mikes_BLK_GT

Correct but I think you can only get them with manual trans like the brembo package