one of the worst things i did in my opinion was put my exaust on when my car was still just a regular ex. it took away from some low-end torque, therefor making it a little less every-day drivable. also, the sound just drove me crazy whenever i had to drive it more than a few miles. i say get an intake, which only makes the engine roar when you WANT it to, and still idles quietly. it's cheap and adds some top-end hp. btw, the afc wouldn't do you much good performance-wise unless you had something more done than just bolt-ons (not including turbos/superchargers). it is fun to look at though
i've had a set of pulleys on my car for about a year now, and they free up some strain from your engine, therefore putting a bit more on the pavement. i'd suggest them as a good upgrade. i would not suggest putting much on your car that will draw attention, like loud stuff or wierd lights or anything. i only have an exaust still cause of my turbo. otherwise, it would go bye-bye on ebay.