5.3 Truck engine mods?

[70rs]

Can anyone here tell me the best mods to perform to a 2008 5.3l /auto trans combo ?
It is 315hp stock. And just to be clear, it is from a 1/2 ton truck.
I'd like to shoot for 375 to 400 hp and keep it NA.
Which intake? Cam? Other mods?
And does anyone know how much the stock 4sp auto trans will take for power before it pukes?

Thanks for any input, I am pretty new to the whole LS thing but am forging ahead.