Well, it’s a basic tune for testing. It also might be lugging at 2500 in 3rd gear. You’re running in manual, so it can’t downshift. So, there's a lug, then it takes off. When it takes off, the rattle immediately goes away. I’m not concerned about it; I just reported it. If the radio was on, you’d never have known. Heck, it may do that without a tune causing it.
Edit: I had Livernois on my edge st. It was a marked improvement, even in normal mode. That said, I wasn't happy with the 8-speed transmission. I also dont feel that had anything to do with them, and Id use them again.