I 100% agree with this being a must. I want to know my car is in perfect shape before it hits the dyno. Why would u want to find a boost leak after ur loaded up on the dyno? Plus as a shop its good have have a compression check done beforehand so if theres an issue u can deny the tune. I'm sure no shop wants to tune a hurt motor and then have there shop bad mouthed saying "oh this shop is horrible" and "this tuner blew my motor". I would do the same thing if I was a shop. It protects them and can save u as a customer money in the long run and ensure the best tune possible