[Galaxy S II General] red.hat:
Disclaimer alert: I am in no way responsible for any damage inquired while performing any of the changes listed below. If you are not comfortable with tweaking your device please feel free to use built in option in Siyah's Kernal. This is just an option and it is something I have tried on my phone with success. I am not using a stock battery, but rather a 2000MAH.

I have NeatRom Lite V1.1 + Siyah Kernal (Slick Sale) installed on my phone. This was created by Sale (his work on this rom is increadible). Samsung's stock kernal has been replaced by Siyah's kernal SGS2v.3.3.2. This version has touch CWM which makes flashing fun. To tweak the kernal, I installed ExTweaks (from the market. Extweaks has the option for battery, performance and defualt settings (these are enabled after a donation). This same settings can be performed in recovery. Siyah has the kernal tweaked for optimization for battery and performance. You can select this in recovery (scrolling down to kernal specific options and the choosing either battery or performance) and it will be impleted during boot up.

However if you feel bold you can tweak the kernal using Ex Tweaks. These are my settings below ( they are by no means a rule of thumb)

Note. I have noticed that the screen consumes most of the power from the battery. If you are able to reduce your screen brightness to about 40% instead of being at automatic, you will get additional time on your phone.

SETTINGS (CPU):

GENTLE_FAIR_SLEEPERS = On

ARCH_POWER = On

CPU Hotplug = Default

CPU IDLE Mode = AFTR + LPA (default)

Smooth Scaling Level = 800Mhz

SCHED_MC = 2

CPU Undervolting = -50mV

CPU Step Count = 18 (All available)

Default CPU Governor = pegasusq

Default CPU Scheduler = sio

Scaling Max Freq = 1000Mhz

Scaling Min Freq = 200Mhz

SETTINGS (GPU freq):

GPU Freq Step 1 = 66Mhz

GPU Freq Step 2 = 133Mhz

GPU Freq Step 3 = 267Mhz

SETTINGS (GPU voltages):

GPU Voltage Level 1 = 800mV

GPU Voltage Level 2 = 850mV

GPU Voltage Level 3 = 900mV

SETTINGS (other):

Screen settings stock.

Vibration intensity = 2

Touchmovesensitivity =5 pixel

Min_BL =30

Min_Gamma=1

Max_Gamma=24

Other setting without undevolting.

SETTINGS (CPU):

GENTLE_FAIR_SLEEPERS = On

ARCH_POWER = On

CPU Hotplug = Default

CPU IDLE Mode = AFTR + LPA (default)

Smooth Scaling Level = 800Mhz

SCHED_MC = 2

CPU Undervolting = No undervolting

CPU Step Count = 18 (All available)

Default CPU Governor = pegasusq

Default CPU Scheduler = sio

Scaling Max Freq = 1000Mhz

Scaling Min Freq = 100Mhz

SETTINGS (GPU freq):

GPU Freq Step 1 = 40Mhz

GPU Freq Step 2 = 133Mhz

GPU Freq Step 3 = 267Mhz

SETTINGS (GPU voltages):

GPU Voltage Level 1 = 800mV

GPU Voltage Level 2 = 850mV

GPU Voltage Level 3 = 900mV

SETTINGS (other):

Screen settings stock.

Vibration intensity = 3

Touchmovesensitivity =5 pixel

Min_BL =40

Min_Gamma=0

Max_Gamma=24

Please note Geko95gek has three different settings and it should work if you are in the mood for an adventure.

Download Links.

NeatRom Lite

Siyah Kernal

ExTweaks (Google play Store)

Useful sources

Geko95gek http://xdaforums.com/showpost.php?p=26755476&postcount=850

Droidphile's article http://xdaforums.com/showthread.php?t=1369817

Special thanks and credit to the following:

Sale (awesome rom and excellent support)

Gokhamoral (great kernal)

Geko95gek (examples of tweaks)

Droidphile (Write up of governors).

Sample shorts of my usage.