No, but i used to see them with minor xp8 parts on ebay from time to time.
If he takes the time to come here and promote his products, he's probably pretty reliable. Because word of mouth on the internet spreads at light speed.
So he does you right, and you tell 2 people, they tell 4 and so on, he does you wrong, and you tell the entire mustang community.
Yes your car will get louder, with cats not too much, but you will notice, you run no cats and your neigbors won't wan't you starting the car after 10 pm.