Exhaust mods

I have a chevy 1500HD with 4in lift... I have Dual in Dual out flowmasters... looking to put tips on tomorrow, should i go with 4in diameter or 5in? looking for great sound and looks they will be kind of hidden coming from up underneath angleing down and out behind tires... Can not decide on the 4s or the 5s just want it to sound as good as i can get it.. please help!

---------- Post added at 07:52 PM ---------- Previous post was at 07:20 PM ----------

need help before tomorrow mornin...