Modding city/castle income?

Ok, I'm trying to implement a mod for making a 0.5 years/turn game more realistic. I've come up with four major things to change to make it work:

1.) Make all building build times 4x greater (so they take the same number of years as vanilla buildings).
2.) Cut population growth by 1/4.
3.) Cut unit upkeep by 1/4.
4.) cut city/castle income by 1/4.

Now, I have 1-3 down (I know which files to mod), but does anyone know the mechanics behind city/castle income and how its derived? Are there files that can be modified to make a 1/4 cut in income?

I want to make it so that the vanilla 1 turn, 2 year income of a city is equal to the 4 turn, 2 year income in a 0.5 year/turn game.

descr_settlement_mechanics.xml, the SIF entries.

Quote:

---

Originally Posted by Lusted

descr_settlement_mechanics.xml, the SIF entries.

---

Excellent. Thanks a million!

Are we sure city/castle income is not scaled automatically through timescale?