Found it! Snoop Dogg's is called "Aint Nuthin but a G Thang" and Twista's is called "Mobster Anthem".
Apparently the synth sound is well known and called "the west coast whistle".
__________________
H̓̇̅̉yͤ͏mͬ͂ͧn͑̽̽̌ͪ̑͐͟o̴͊̈́͑̇m͛͌̓ͦ̑aͫ̽ͤ̇n̅̎͐̒ͫ͐c̆ͯͫ̋ ̔̃́eͯ͒rͬͬ̄҉
|