Hey I'm Chris, I'm 15 years old and I had my first serve measurement the other day and I was consistently hitting serves at around 63-68 mph with a top speed of 70mph. Pro Tennis is a little off the mark, unless some lucky miracle happens but I was just wandering what it would take to get a serve over 100mph? I use 2 racquets depending on how I feel, one being a wilson pro staff six one 95 and another being a HEAD MICROGEL RADICAL MP... I obviously serve faster with the Head as it gives me that little bit more power. I do a lot of exercise and body stuff, I have pretty strong muscles and my technique is different as my coach says. However I am not done growing and I'm only around 5ft6.5 inches tall... do I need to grow a little taller to gain some decent speed on my serves? Thanks for the help!