There are so many cheat,from car cheat until gun cheat but the cheat wont make this game challenge anymore,i suggest you not use this cheat if you still can do the mission by your self but,if you cant,i have some cheat that maybe can help you.(to use it just type in the game)
This is the cheat :
Cheat                             Effect
LXGIWYL                     Weapon Set 1, Thug's Tools
KJKSZPJ                       Weapon Set 2, Professional Tools
UZUMYMW                  Weapon Set 3, Nutter Tools
HESOYAM                    Health, Armor, $250k
OSRBLHH                     Increase Wanted Level Two Stars
ASNAEB                       Clear Wanted Level
AFZLLQLL                   Sunny Weather
ICIKPYH                      Very Sunny Weather
ALNSFMZO                 Overcast Weather
AUIFRVQS                   Rainy Weather
CFVFGMJ                     Foggy Weather
YSOHNUL                    Faster Clock
PPGWJHT                     Faster Gameplay
LIYOAAY                    Slower Gameplay
AJLOJYQY                   Peds Attack Each Other, Get Golf Club
BAGOWPG                  Have a bounty on your head
FOOOXFT                  Everyone is armed
AIWPRTON                Spawn Rhino
CQZIJMB     Spawn Bloodring Banger
JQNTDMH    Spawn Rancher
PDNEJOH     Spawn Racecar
VPJTQWV     Spawn Racecar
AQTBCODX  Spawn Romero
KRIJEBR     Spawn Stretch
UBHYZHQ     Spawn Trashmaster
RZHSUEW     Spawn Caddy
CPKTNWT     Blow Up All Cars
XICWMD     Invisible car
PGGOMOY     Perfect Handling
SZCMAWO     Suicide
ZEIIVG     All green lights
YLTEICZ     Aggressive Drivers
LLQPFBN     Pink traffic
IOWDLAC     Black traffic
AFSNMSMW     Boats fly
BTCDBCB     Fat
JYSDSOD     Max Muscle
KVGYZQK     Skinny
ASBHGRB     Elvis is Everywhere
BGLUAWML     Peds Attack You With Weapons, Rocket Launcher
CIKGCGX     Beach Party
MROEMZH     Gang Members Everywhere
MROEMZH     Gangs Control the Streets
AFPHULTL     Ninja Theme
BEKKNQV     Slut Magnet
BGKGTJH     Traffic is Cheap Cars
GUSNHDE     Traffic is Fast Cars
RIPAZHA     Cars Fly
JHJOECW     Huge Bunny Hop
JUMPJET     Spawn Hydra
KGGGDKP     Spawn Vortex Hovercraft
JCNRUAD     Smash n' Boom
COXEFGU     All Cars Have Nitro
BSXSGGC     Cars Float Away When Hit
XJVSNAJ     Always Midnight
OFVIAC     Orange Sky 21:00
MGHXYRM     Thunderstorm
CWJXUOC     Sandstorm
LFGMHAL     Mega Jump
BAGUVIX     Large Health Boost
CVWKXAM     Infinite Oxygen
AIYPWZQP     Have Parachute
YECGAA     Have Jetpack
AEZAKMI     Never Wanted
LJSPQK     Six Star Wanted Level
IAVENJQ     Mega Punch
AEDUWNV     Never Get Hungry
IOJUFZN     Riot Mode
PRIEBJ     Funhouse Theme
MUNASEF     Adrenaline Mode
WANRLTW     Infinite Ammo, No Reload
OUIQDMW     Full Weapon Aiming While Driving
THGLOJ     Reduced Traffic
FVTMNBZ     Traffic is Country Vehicles
SJMAHPE     Recruit Anyone (9mm)
BMTPWHR     Country Vehicles and Peds, Get Born 2 Truck Outfit
ZSOXFSQ     Recruit Anyone (Rockets)
OGXSDAG     Max Respect
EHIBXQS     Max Sex Appeal
VKYPQCF     Taxis Have Nitrous, L3 Bunny Hop
NCSGDAG     Hitman In All Weapon Stats
OHDUDE     Spawn Hunter
AKJJYGLC     Spawn Quad
AMOMHRER     Spawn Tanker Truck
EEGCYXT     Spawn Dozer
URKQSRK     Spawn Stunt Plane
AGBDLCID     Spawn Monster
IFIRSTDOZ     Never Wanted
CAINEMVHZC     Infinite Health, except for explosions and falls
allcarsgoboom     All Cars Explode
Plain Text Cheat Codes

Type these codes during gameplay. The set code can be uppercase or lowercase.
Cheat     Effect
PROFESSIONALSKIT     Weapon Set 2, Professional Tools
PLEASANTLYWARM     Sunny Weather
TOODAMNHOT     Very Sunny Weather
SPEEDITUP     Faster Gameplay
SLOWITDOWN     Slower Gameplay
VROCKPOKEY     Spawn Racecar
WHERESTHEFUNERAL     Spawn Romero
CELEBRITYSTATUS     Spawn Stretch
TRUEGRIME     Spawn Trashmaster
WHEELSONLYPLEASE     Invisible car
STICKLIKEGLUE     Perfect Handling
GOODBYECRUELWORLD     Suicide
FLYINGFISH     Boats Fly
BUFFMEUP     Max Muscle
BLUESUEDESHOES     Elvis is Everywhere
ONLYHOMIESALLOWED     Gang Members Everywhere
BIFBUZZ     Gangs Control the Streets
NINJATOWN     Ninja Theme
EVERYONEISPOOR     Traffic is Cheap Cars
EVERYONEISRICH     Traffic is Fast Cars
CJPHONEHOME     Huge Bunny Hop
ITSALLBULL     Spawn Dozer
FLYINGTOSTUNT     Spawn Stunt Plane
FOURWHEELFUN     Spawn Quad
OHDUDE     Spawn Hunter
NATURALTALENT     Max All Vehicle Skill Stats
PROFESSIONALKILLER     Hitman In All Weapon Stats
HELLOLADIES     Max Sex Appeal
WORSHIPME     Max Respect
ROCKETMAYHEM     Recruit Anyone (Rockets)
GHOSTTOWN     Reduced Traffic
FULLCLIP     Infinite Ammo, No Reload
CRAZYTOWN     Funhouse Theme
STATEOFEMERGENCY     Chaos Mode
ROCKETMAN     Have Jetpack
BRINGITON     Six Star Wanted Level
KANGAROO     Mega Jump
SCOTTISHSUMMER     Thunderstorm
NIGHTPROWLER     Always Midnight
BUBBLECARS     Cars Float Away When Hit
JUMPJET     Spawn Hydra
SPEEDFREAK     All Cars Have Nitro
MONSTERMASH     Spawn Monster
Testeducationalskills     No Wanted Level
STINGLIKEABEE     Mega Punch
OLDSPEEDDEMON     Spawn Devil


<notice>
Sorry for the cheat format but the cheat will 100%work