swollynn

New to the group. 3rd mustang. Had 84, 08 GT, now have 2014 GT/CS auto with 3:15.1 stock. Lowered, RTR wheels, Ford racing touring exhaust. About to get programmer and CAI. Anyone running 3:55.1 or 3:73.1 in this setup?

P51C

Not advisable. The gears inside the box are a lot shorter and the overall first gear ratio is similar to a stick car with a 3.73 on the 3.15s already.

The biggest gains on the auto are by getting a looser converter and a tune. Steep gears will just incinerate tires.

swollynn

I know on the 2015 the 3.55:1 was an option in the auto just wondering if anyone was running them in a 2014. 3.55 says RPM @ 75 is 2270.

P51C

3.55 is an option on the 15s. Standard is still 3.15. The 15s have more mass to shift, likely leading to the offer but, from a pure acceleration Mac standpoint, the 3.55 will be slower due to traction issues and the number of shifts over a fixed distance. The fastest auto s197 cars in the nation are on 3.15 or 3.31.

It's like 3.73 on the stick cars. It can feel faster but it really isn't, over a 3.55 car, say.

Everything I've said is massively confirmed in practice, if you look around the web a bit.