I love my hp tunners... I have used it on several cars.. not my l99, but none the less I can scan and dig around and learn....... I dont have the pro I bought my hp for 499.00 with 8 credits... took car of my buddys Ls1 and is so nice to have the abilith to go in when ever we want and change stuff.. If he wants to go back to stock, it just a button click away.... any time any place...