Yeah, as it's naturally aspirated it will be quieter, turbos quieten exhaust noise, and superchargers make them louder. Mine was also extra loud as it only has a backbox as a silencer, everything else is straight pipe.
Yours does need to be louder! Have you considered a screamer pipe?
NH - would this one pass track day noise tests? I seem to recall you had to put a can over your exhaust because of this?
(I got told my car, at 84 decibels, was "shamefully quiet").