It sounds like the valve train as the new disc injectors are pretty quiet and you can check this (valve or injector) with a stethoscope: careful the first time as you will think the first one is it. If it is an injector or rocker you will REALLY notice it as you work your way across the top of the injectors and valve cover.
It could also be piston slap, mine does that, and I notice it the most not so much at idle as I do with light acceleration at about 22-3000 rpms: sounds like either a lifter or spark knock. It's slap and is harmless.
Just hammer hell out of it: that is what it was made for and if it breaks they gotta' fix the thing . .