exhaust questions

chads370z

Hey guys I just did the res deletes on my 09 370z m6 and it sounds awesome. However with the rest of my exhaust system being stock, I can only hear the raspy sound above 3500 rpm. I have a local muffler shop that will do any modification/customization I'm willing to pay for. so my question is:
if I keep the stock exhaust piping and have them cut out the Y, turning it into a true dual setup, what will I gain or lose? I want it to sound good and I believe I can do that without buying a complete system. I was listening to some 370z exhaust sounds on youtube and the flowmaster sounds awesome to me. I also like the magnaflow but there's no way to tell until it's actually on my car. I know most will say buy a complete exhaust system and put that on instead. but if I were to, I'd probably get 2.5" which is the same as is on there now. Any suggestions?