you can get both stats to max it just costs alot of metal and candies, just bc there are 5 story scenes doesn't mean the stats can only go up 5 times, i got My Super Pershing to 5 affection and i still have the option to increase the stats more im pretty sure you get 2 upgrade points every 1 story scene, so when your done it leaves you with 10 upgrade points to max both stats out with