Dash4237

Hello all, I'm hoping someone can help me out with this noise can't place it. I had my radio off the other day driving and noticed the exhaust stock non-NPP sounds a little louder and it's a low whining noise coming from car (doesn't sound like blower). I'm not sure if it's the cats that finally went... I'm pushing a little over 600 rwhp and I was just weighing my options on switching to a V3-ti blower head now next week or ordering longtube headers and 3.47 pulley. This might make my decision a lot easier on my next mod if the cats are blown!! I attached two sound clips, hopefully someone can make out the noise over my blower sound! Any thoughts??