The smaller the boxes the louder the sound will BE!!!
I have Cats removed, joined by 63mm (like SS) X-pipe and finished with free-flowing boxes (63mm inside diameter) completed with 90mm tips...
Sounds

horrifying , some resonance but not too much...
I wish I'd still had a clip of it

May be someone has MY exhaust sound recorded and can post it or send it to me pls

...