3 inch is too big for a V6. Buy a second hand SS stock dual system and all the necessary hanger, rubbers and heat shield - fit that up and change the rear mufflers to straight through. That will make your omega plenty loud enough.
Will a X force 2.5" cat back system be good. And also what to you mean by straight through muffler where can i buy that. The X force site only sell Oval mufflers are they straight through? And also will the choice of exhaust tip make a difference? And what inlet and Outlet center size should I get. Is the bigger the inlet size the louder the exhaust?
trust me a real loud exhaust get to be a real pain real quick, good at first but when your half deaf from the drone on the freeways youll wish you didnt do it and youll get sick of having to idle past cops because its too loud ive been there and done that.
i just got my vy v6's exhaust done... pacemaker extractors, high flow cats and 2.5 in sports exhaust... got the muffler so its reasonably quiet below about 2500rpm and then it gets nice and loud... it does sound a little bit ricer but it has a really nice crackle to it so im liking it for a v6
my advice: dont try and make it sound like a v8 cause its lame... just try and get the best performance out of it and at the end of the day youll probably end up with a decent sound for a v6... if you beat someone down the 1/4 mile youll have all the answers you need to the whole your car sounds crap jokes lol
EDIT: pretty much no drone on the highway... you kinda have to strain to hear it