I have a 99 6.8L and I wanted to modifiy my intake tube rather than buying a intake kit for $250+ I have a K&N in it but I want better flow throw the tube is the 3 inch tube big enought or do I need to go bigger with it

 

I think that you'll be okay with it (it being stock I assume) unless you're looking at other performance upgrades.

 

Its getting duel exhaust and chipping it