Well, you will have different opinions on that subject. I tend to do all my mods and then do the tune. Problem is, someone always comes up with another "go fast" part that I just have to have. Then, it is re-tune time, lol. That hasn't happened that often, but it does happen. My reasoning is, you are messing with electronics, and I don't want to tap that area anymore than I have to. You will enjoy it I am sure. It stretches a few parameters you will notice immediately. They set the parameters. Unless you have something specific in mind. They will raise your top end limiter, not that any of us here would ever try to move beyond 158 mph.....lol