I have the Magnaflow Competition Catback (non quad tips) with a Magnaflow High Flow Catted X.
Yes, it's loud....apparently.
I don't consider it loud but others mention it to me quite often.
Make sure you're listening with a good set of headphones or speakers.... There is a lot of bass in the note due to the cats.
2014 Mustang GT Premium (deep impact blue)
Too many mods to fit in my sig.
Follow my build list on my blog
. (still updating mods installed so far)