I have a 1999 Silverado Z71, it has the 5.3 and was wanting to give it more power, but I am on a small budget. I was just wondering what some of the better mods would be for the money. The only thing that I have done to it is threw a K&N on it, and I'm getting Flowmasters put on it. Any info would be great.  

A cam swap and performance tune will really wake up your 5.3L

What is your "small" budget?  

my budget is between 500 and 1000, i hate to go any higher then that for now. Do you have any suggestions on the brand, and size of cam?  

use a summit cam a bit cheaper compcams etc.Call them they will help you and put some headers on it oh also a chip or programmer these things should really wake your motor up