Can't understand this dyno sheet
 

It's from MD's website
http://www.motordyneengineering.com/...tAnalysis2.gif

Why does hp dip around 5700 then return around 6000RPM in these cars.....shouldn't it be a smoother curve??

I would guess it's the threshold for the variable valvetrain engagement. If you look closely, the entire event duration is only around 300 rpm. You wouldn't even feel that when driving foot-to-the-floor.