Dear Jai Gupta,
It’s great that you want to take the next step with the Energization Exercises of Paramhansa Yogananda. Certainly you should focus more and more on the energy flow to the body parts — rather than only on creating physical tension — as energy is a central focus of these exercises. Use your power of visualization: visualize abundant energy flowing to the center of center of the body part(s) that you are tensing.
As for whether you should reduce the physical intensity, that depends on how much physical intensity you currently have when practicing. Until you are highly advanced, there should always be significant physical engagement when doing these exercises. But if you are straining, clenching your jaw, holding your breath, finding yourself out of breath, feeling lots of blood rush into your face, then yes, it would be good to reduce the physical intensity, so you can be aware at the subtler level — energy — and feel the energy pouring into the body parts.
Blessings on your practice,
Nayaswami Gyandev