Otherwise, get out there an get going faster than 40mph. No one should own a Mustang for more than 10 minutes and not have gone faster than 40mph.
I went less that 40 mph for the one hour drive home due to traffic after picking up my new GT.
To the OP, as others said, just drive normally and you won't even notice what wheels are powering it. If you plan on driving it in the winter, I strongly recommend a good set of snow tires. I had a 2000 V6 years ago and the tires made a world of difference.