Many people on stangnet have told me ASP are the best for 5.0, they are 74 bucks, you can find the cheaper if you look. Someone on the forums dynoed 9 rwhp with just pulleys, but the car was stock.
CHeck out here.
2003 DSG Cobra
-2.2L KB, 60lbs Injectors, Single Blade TB, SCT2400 MAF, Kook's LT's, Kook's High-Flow Catted X-Pipe, Magnaflow CB, JLT RAI, MGW Short-Throw, H&R Race Springs, MM CC Plates, MM Bumpsteer, BF IRS Brace, BF Idlers, and AFS 18 Chrome Reps w/ R888s