really loud exhaust

this guy at my school has a civic hatch and claims to have a ctr engine in it. when he starts it up and drives, it sounds quiet, and it has a stock looking exhaust. but when he floors it the thing is really loud. ive taken off my exhaust and ran straight header on my b18 and it still isn't as loud as his hatch. ive seen a couple hondas that are like this, how do they get it like that? i dont like it that loud but im just wondering how they get it like that.

electirc cut out?
i have no idea open header is really freaking loud