High my name is CHarlie i live up in Alaska i have a 1999 Z71 LS Silvarado 5.3L. SO far its pretty much stock. I took off the muffler and put a glass pack in its place and dumped it after the Glass pack so it has a nice deep rumble witha little pop if you rev it up. i noticed a nice little increase in Gas milage and power. I am wondering what else i can do that can give me more power without spending an arm and a leg. I love this truck as it is but i want more. I raced my boss on the way home a couple days ago and he is running a 2000 Ford F250 with the V10 and beet him. he has been trying to tell me that his v10 is faster than my v8 for the simple fact that its bigger than my engine but i proved to him the other night that chevy prevails!