I remember when I bought my first 3" cat back for the 33....Me, Justin and James fitted it up at James' work, started the car and were instantly devastated...it was so quiet lol
Sold it to GTRGeoff not long after and bought a new one, much louder...
Then went de-cat at the same time as the rebuild/turbo upgrade...Hadn't driven the car for a few months....I remember picking it up at RE, left RE later that night....had the windows down and the stereo off.....was deafening and sounded insane (combination of new turbo/de-cat/ and not having driven it for so long)
After a while you get used to it, obviously it's still as loud, but didn't seem that way to me.