Best Damn Plan and Cardio/Metcon

I got your BDPFNL and I am all set to start tomorrow. Looking forward to the changeup and shorter but intense sessions. My question is this:

My background has been in locally competitive CrossFit athlete for the last few years, but Im looking to change things up and lift heavy for growth for awhile. In order to keep my “engine” in shape, I was planning on doing 4 HIIT/Cardio/Metcon type workouts per week, in addition to your programming. Do you have any specific recommendations on how to do this with your program? Also, do you even recommend attempting to add that type of training to this program? My dilemma is trying to balance growth with conditioning and I don’t want to be counterproductive.

Thanks.