When you say "stock" holster and mag pouches, I assume you mean those that come with an XD, yes? If so, I think they're fine. Is a Blade Tech (and others) better? I suspect yes, a Blade Tech will allow for a VERY slightly faster draw but If you're looking to be competitive in Production division, it's not the holster that needs changing, it's the gun. Actually, it's PRACTICE but to get the most out of your gear, you'll need to change things if your XD is stock. Better sites, a trigger job, mag well, etc will make a world of difference, much more so than the holster.
That said, I'm glad I kept everything stock for the first year after I started shooting IPSC. I didn't change a thing and used the cheapest of all holsters, an Uncle Mikes. I wasn't trying to beat anyone, just learn the game and learn how to shoot properly. After that first year, I knew exactly what I wanted. I now shoot a custom Single Stack gun with Blade Tech gear. My original Production gun (a Beretta) sits in the safe save for an occasional plinking outing.