I have a 3" with the bigger resonator.
Is very quiet lol, no way that its over. After putting it on i was actually wondering if i had remembered to take all the stuffing out of the pipe sections lol.
Great performance upgrade tho, spools much nicer now, and JJR do great prices on them. I was quoted $600 extra by the so called "wa supplier" of these than just jap.
So you pretty much cant go wrong with either but given the choice, go the 3.5 from the cat back with the oval resonator. U will have no troubles.
But just so you know they do hang kinda low.
Cheers,
Dragonforce