Here is my plan, in the order I plan to do it.
New wheels with summer tires. I'm not sure what wheels. Probably not larger than 16 inch.
Slightly lower/stiffer suspension. Probably just a Ford Racing spring kit and some new shocks or something like that.
Turbocharger. This is a big maybe. I'm not ape**** over having a car that can do 0-60 in under 7 seconds. But I would like my Fiesta to be about as fast as my current Focus ST (around 7.5 seconds to 60) and if the Intake/Exhaust/Tune can't get me there I'll probably pick up a low-boost turbo kit. And have someone else install it, because that's way over my head.
I'm not sure if I'll buy a body kit. I'm not a huge fan of the optional one. If I don't buy the Euro spoiler I'll probably buy some sort of larger spoiler in the aftermarket.
I'm also torn about how to approach the sound system. Sync SEEMS like a no-brainer. But my problem with it is that with the way technology advances, it will probably feel out of date in 3 years. And in spite of being a huge tech-geek when it comes to PC and other home electronics, I actually rather dislike tech in my cars. If I don't get the Sync & Sound, I'll pick up a stereo upgrade - just some higher quality speakers - at some point down the road.