Any suggested house rules to make the game more challenging? (VI expansion)

[Brandy Blue]

Something like 130-140 turns, a smaller map offering less cultural divergences and making the possibility of lands conquered more plausibly realistic with less factions and less options would have helped the AI greatly and enhanced his performance helping make the game more challenging/on the same footing as the AI, and hence more fun

But ... but ... OK, I'm confused. Hadn't they already published that game under the name Shogun Total War?