I just tested this out, and from my experience at least, you have to change both numbers in the diagram above to get the crazy hp numbers (if that's what you're going for). Change the single byte associated with that part to "FF" (or lower for less hp) and the part with 4 bytes to "00 00 FF FF".
Basically just the way he shows in the pic, but I didn't see any effect until I changed the single byte to a higher digit.
I just started trying this out the other day so no expert by any means, but that's what worked for me. (Had to go get an oil change first thing for it to take effect as well).