I put a set of 50# limbs on my Alien X a couple weeks ago. Just measured everything - did a straight limb swap - re-checked the measurements and everything was the same so I didn't re-tune or anything. Shot around 200 arrows thru it the past week and all seemed to be well.
Since it is the bow I am going to use for spring Turkeys, today, I thought I would put a couple broadheads on and see if they still impact the same.
So I go outside and set up at 25yds (my top pin) and put a broadhead in the target. Load a FP tipped arrow and:

So - guess I wont change the tune...