Pypes is the bottom of the barrel as far as quality control, design and workmanship. BBK and MAC are the first "decent" units. If you get the stock ceramic coatings that come with either its not a very good one so be warned about that or at least it wasn't when I bought sets of them in the mid 2000s.
If you want a set that is guarandamnteed to fit properly and give you zero problems get the Kooks. SLP made a badass set too but they are now discontinued. Might be able to still find them somewhere though.
2000 Mustang GT Steeda build #48. Bolt ons, suspension, Novi 2000.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.