[Galaxy S II Q&A, Help & Troubleshooting] eskriminal:
seems to be varying by the person, 34 is stable for many, but some are using 33 instead

I'm on 34 with the settings oriented for battery, as follows

boot_boost=1200000
wakeup_boost=4
scaling_max_freq=1000000
scaling_max_freq_oc=1000000
scaling_min_freq=200000
GENTLE_FAIR_SLEEPERS=off
ARCH_POWER=on
enable_mask=3
enable_mask_sleep=3
busfreq_up_threshold=30
scaling_max_suspend_freq=800000
scaling_min_suspend_freq=200000
standby_freq=200000
cpu_voltage_switch=on
CPUVOLT1=1425
CPUVOLT2=1400
CPUVOLT3=1325
CPUVOLT4=1300
CPUVOLT5=1200
CPUVOLT6=1150
CPUVOLT7=1100
CPUVOLT8=1050
CPUVOLT9=1000
CPUVOLT10=975
CPUVOLT11=950
CPUVOLT12=950
CPUVOLT13=900
CPUVOLT14=900
CPUVOLT15=875
CPUVOLT16=950
scaling_governor=nightmare
up_threshold=70
up_threshold_at_min_freq=60
sampling_rate=60000
sampling_down_factor=1
freq_step=20
down_differential=5
freq_for_responsiveness=400000
down_threshold=30
cpu_up_rate=10
cpu_down_rate=1
inc_cpu_load_at_min_freq=90
inc_cpu_load=80
dec_cpu_load=80
freq_for_responsiveness_max=600000
freq_step_at_min_freq=5
freq_up_brake_at_min_freq=50
freq_up_brake=50
freq_step_dec=10
freq_step_dec_at_max_freq=30
up_sf_step=50
down_sf_step=50
hotplug_enable=1
hotplug_freq_fst=500000
hotplug_freq_snd=200000
up_load=65
down_load=30
scaling_governor_sleep=darkness
up_threshold_sleep=90
up_threshold_at_min_freq_sleep=70
sampling_rate_sleep=60000
sampling_down_factor_sleep=1
freq_step_sleep=20
down_differential_sleep=5
freq_for_responsiveness_sleep=300000
down_threshold_sleep=30
cpu_up_rate_sleep=40
cpu_down_rate_sleep=40
inc_cpu_load_at_min_freq_sleep=80
inc_cpu_load_sleep=80
dec_cpu_load_sleep=80
freq_for_responsiveness_max_sleep=800000
freq_step_at_min_freq_sleep=20
freq_up_brake_at_min_freq_sleep=50
freq_up_brake_sleep=50
freq_step_dec_sleep=10
freq_step_dec_at_max_freq_sleep=10
up_sf_step_sleep=30
down_sf_step_sleep=30
hotplug_freq_fst_sleep=500000
hotplug_freq_snd_sleep=200000
up_load_sleep=60
down_load_sleep=30
cortexbrain_read_ahead_kb=0
scheduler=bfq
sleep_scheduler=bfq
auto_oom=on
oom_config_screen_on=default
oom_config_screen_off=medium
dirty_background_ratio=15
dirty_ratio=20
zramtweaks=4
swappiness=0
cortexbrain_uksm_control=off
mali_use_vpll=off
mali_gpu_utilization_timeout=500
GPUFREQ1=108
GPUFREQ2=108
GPUFREQ3=160
GPUFREQ4=200
GPUFREQ5=267
GPUVOLT1=850
GPUVOLT2=850
GPUVOLT3=1000
GPUVOLT4=1050
GPUVOLT5=1050
GPUTHRESHOLD1UP=80
GPUTHRESHOLD2DOWN=60
GPUTHRESHOLD2UP=80
GPUTHRESHOLD3DOWN=60
GPUTHRESHOLD3UP=80
GPUTHRESHOLD4DOWN=60
GPUTHRESHOLD4UP=80
GPUTHRESHOLD5DOWN=70
min_bl=50
min_gamma=0
max_gamma=23
power_reduce=on
user_cb=127
user_cr=127
mdniemod=off
user_gamma_adjust=-15
fbearlysuspend_delay0=50
pwm_val=75
tsp_slide2wake=off
mdnie_shortcut_enabled=off
negative_tweak=1
gesture_tweak=off
TOUCHSCREEN1=50
TOUCHSCREEN2=40
TOUCHSCREEN3=12
TOUCHSCREEN4=53
TOUCHSCREEN5=38
TOUCHSCREEN6=47
TOUCHSCREEN7=50
TOUCHSCREEN8=12
TOUCHSCREEN9=42
TOUCHSCREEN10=47
jb_sound_fix=off
soundgasm_hp=0
sound_volume1=0
sound_volume4=0
sound_volume2=0
sound_volume3=0
notification_enabled=on
bln_switch=0
notification_timeout=0
led_timeout_ms=3000
blnww=on
led_fadeout=on
led_on_touch=off
touchkey_brightness=3000
dyn_brightness=off
crontab=off
cron_drop_cache=off
ad_block_update=off
cron_db_optimizing=off
cron_clear_app_cache=off
cron_fix_permissions=off
cron_zipalign=off
gpsregion=No_GPS_Zone_changes
usb_mode=default
auto_mount_sd=on
chargecurrent1=650
chargecurrent2=650
chargecurrent3=500
default_stats=on
init_d=off
logger=off
install_root=on
cortexbrain_background_process=1
android_logger=auto
cortexbrain_auto_tweak_mobile=off
cortexbrain_auto_tweak_mobile_sleep_delay=30
cortexbrain_auto_tweak_wifi=off
cortexbrain_auto_tweak_wifi_sleep_delay=30
cortexbrain_firewall=on
cortexbrain_tcp=on
cortexbrain_tcp_ram=off
cortexbrain_ipv6=off
cortexbrain_cpu=on
cortexbrain_memory=on
cortexbrain_battery=on
cortexbrain_eco=off
cortexbrain_eco_level=5
cortexbrain_system=on
cortexbrain_kernel_tweaks=on
cortexbrain_io=on
usbserial_module=off
usbnet_module=off
cifs_module=off
eds_module=off
defaultrom=0

careful though, the under volt is probably too much for your phone