You will never get the sound of a v8 but if you want the loudest, just remove the muffler ant go straight pipe!. I have y pixie and no muffler and its ridicoulousy loud. You will have to deal with the rasp, the more you open up the flow, the more an issue it will be. Most people hate it and add a couple magnaflow mufflers to the Catback.

URD catback but swapped the muffler with a flowmaster super44


https://www.youtube.com/watch?v=HfLovrSzqkw

I have a jardine 2.5 catback and it is not super loud. With the short tube thorleys I just had installed though it actually sounds alot meaner/deeper then it did for sure. I would try to find one to hear in person or keep listening to sound clips. It would suck to get stuck with something you dont like. Im one of the few that doesnt like the sound of the dtlts and y pipe I didnt want to have to swap headers every 2 years anyway here in califoria. I love the sound of my truck with the jardine catback/short tube thorleys/urd tcai though. Mean enough to know I aint stock but quite enough for cruising with no drone in the cab. Good luck with your setup.

Im running 2.5in exhaust with a custom tip and a magnaflow muffler. Its quiet enough in low RPMs then anything above 2500 it gets loud