There is an issue SOMEWHERE in your setup. 330 on 5's is a little below par.
Well the RP one is twin 3 inch all the way. I'm thinking about not running the twin's front pipes, coming out the back of the turbo in a 4 inch then splitting that into a twin 3 inch to meet up with the "catback". Each gate will pluimb into 1 of the 3 inch pipes.
The SR result im reffering two, we overlayed my 2.8 and 5's. This SR with a 6262 had MORE bottom end grunt and made an extra 10 kw up top.