That first link is from 2003. The guns and measuring system have changed since then. They were using physically different guns for stella/davis cup back then(where roddick set his records, clocked it off the strings), so im assuming he was referring to those guns, not the ones used at grand slams/other events. I think the other gun measured around the T on the servers side. I agree about the gun positioning. I have been clocked at upto 120 (im a baseliner though). I did hit a few i thought were much harder than the registerd 120 but showed up at like 105. Seems if you hit the serve directly at the gun it gives you a bit more. Agassi wasnt a typical pro athlete. He wasnt fit or strong until 1997. Go back and look at some video of him, very skinny legs/arm and no chest. Combine that with modern technology (look into what happened when someone accidently put poly into agassi's fram in rome, i think, he was mad, love it and never went back). Agassi was much stronger post 1997 then he was before that. I think he was on steroids but thats another issue.