You probubly wont be able to tell the difference with the 70series.
If your wanting more sound, go atleast a 50 series, and even then it wasnt much different.(i had a 50 on my 05 silverado 5.3)
If you want something that sounds and flows good without being too loud, id go 18" magnaflow.
Youll need 3"in and 2.5 dual out
12 RCSB Express- 5%Tint, Gatorhyde spray-in, Black OEM Tips, Plasti Dip badges and Interior, CBE muffler,AFE CAI, Kenwood DDX370, Ks3.5s, Pioneer 6x9s,BT 964SP lowered on oem chrome 17's and some LEDs... Plenty on the To-Do list
New audio build in progress