I would like to say that the codes for the inventory works like a charm. Thank you so much! But... The code for "Super HP" have a twist: It turns G Creature (William Birkin) Phase 4 have a "Infinity HP Monster". I saved before the fight to check and i took the whole 7 minutes of the battle to measure this interesting effect: Using the code for the ATM Rocket Laucher i indeed couldn't kill the creature with like 40+ rockets... Important to say one thing too: I don't know if it is a side effect of using a lot of codes together since i used the inventory items code plus the 999 ammo in the chest, the full upgraded inventory code (20 items) with the super hp code (a salad!) But... I came to advise you of this since you could be running a no save gameplay full of joy and so happy and this exactly thing could ruin your day. So before it happens... Stay advised! I'll continue to test and see if I can find what happened to this effect happen. Cheers!
[EDIT] Below the code I used for the Super HP:
80010008 D3A8A66D
633EECF7 00000000
28000010 005B8D80
80020008 D3A8A66D
633EECF7 00000000
28000010 005B8D80