Yeah....that is a very solid d-line - I might've been more concerned if you were using a team with a much weaker line. Wait until you use a team with a bad d-line...the difference can be a bit jarring
As you inch upwards on the holding slider, you'll begin to eat into what little pass rush we have and it will hurt the CPU rush on your QB.
Honestly, I would leave it where it is and enjoy having Ngata and company while you can. If it absolutely becomes a game-breaker for you, you can try 51 - but just be aware of the potential consequences.