I havent had any problems except one or too small issues (Good thing for backups) w/ modding my game so far on XBOX.... I have added about 20 cars or so all of which i converted from the PC (And run fine with a bunch on the screen) also Changed tommys skin to a terrioist and fucked with some of the stats for cars and weapons (PCJ600 weighs as much as a bus and plows through cars) Also on top of that I installed Ko-Gars' Multi-Mod, which locks the doors when u get in cars, respawns if you go in the water in certain cars, starts you w/ 100K, makes all the vehicles you are driving fireproof bombproof etc. Starts you w/ 200 Health and Armor, adds nitrous to every car you drive nice speed boost. Heres the cars i have added and have working perfectly...only one that slows down a little bit is Suziki Escudo Pikes Peak from GT3. Im definatly just gonna replace all the cars and if people want maybe post the modded gta3.img on usenet or something. I still gotta change the ingame text to the real car names too. Havent tried yet but im sure it will be a breeze. Im gonna make a crazy stunt video in the next few days too LOL

Banshee - Mitsubitshi Lancer
Cheetah - Ferrari F50
Comet - Lotus Caterham 7
Infernus - Lamborghini Diablo
Phoenix - Opel Speedster
Stinger - Supra MK IV
Sabre Turbo - Suziki Pikes Peak (Gran Turismo)
Deluxo - Saleen 7
Admiral - Porsche Carrera GT
BF Injection - Warthog (Halo)
Glendale - VW Golf GTI
Oceanic - 68 Camero
Stallion - Mercedez CLK GT
Washington - 2004 BMW 325ci Convertible
Angel - Trike
PCJ 600 - Ducati 996
Faggio - Toliet w/ wheels
Baggage Handler (at airport) - Quad 4 Wheeler
Police Car - Police Dodge Viper GTS
Maverick - Go Go Copter (Inspector Gadget) <