You might want to pick up the latest copy of Chevy High Performance, it actually their engine special focusing on the LS1 motor.  They did a comparision on an F-body Camaro I believe where they used the stock LS1 intake, Stock LS6, Stock Truck intake, & the FAST LSX intake.  Believe it or not the truck intake flowed better than both the Stock LS1 & LS6, and was just barely beaten by the FAST LSX.  They where using an ls6 cam and ls6 springs and 1.85 Rollers among a horde of other goodies.  
It is a really good issue that any GM performance junkie should read.
				
			 
			
		 
			
                        	
		         
			
			2007 Silverado NNBS RCSB__4.8 Liter
        True-Flow Drop-In/Stock Air Box(modded)/AirAid MIT, 3" SLP LM1, Shaner Ported 90MM TB, Wheatley Tuned
 
1999 LS1 Z28__Stone Stock for Now