I too have one on a nytro. If the Apex foam is the same as the Nytro, you will feel and be sitting at least 4" taller than the soft stock seat. I added a 3" over stock riser as well.
I had to get the tallest windshield available, but that is my old guy preference.
The cover is top notch quality. I used a doufast staple gun. It only penetrated the seat frame if I preheated the plastic as I went along. I am not an upolsterer at all but the cover stretched easily and looks great.
I think it was worth the money. It puts me in the same seating position as the Poo AXYS....knees below my hips.