[SR2007]

I'm looking heavily into the performance aspect of my 07 E92 328i. I know not much to gain, but hey it couldn't hurt. One of my biggest endeavors is I'm trying to go with a True Dual Remus Quad Exhaust Set Up. I'm assuming that i would have to get a custom y pipe made from the Cat....Right?? is there room for the right side muffler?? Any info or pics would be most appriciated before I pull the trigger. In addition, I'm about to purchase the AFE Stage 2 KAI and BMS power box to help compliment the exhaust. What type of gain might i see? And lastly who do you guys reccomend for a set of headers? I want the most aggressive sound i can pull out while still being legal. Drone is no concern for I'm already half deaf. lol Any Info?????????????