I have used aircraft made for ai with no problems.but for best results add real world textures to the default aircraft and use those to fill in the slack at airprots with not much traffic.its just a trial and error thing with non ai aircraft add one in at a time and test it.but with so many aircraft out there that are made for ai use it just a hasel to try any thing eles.but i am useing mike stones gmax Piper Malibu Meridian in ai with good results.just stick with gmax made aircraft they make the best ai.but you cant just swap airfiles you have to add the aircraft cfg file as well then you run into problems with contact points and light placements on the aircraft and its not as simple as just useing ai made aircraft.and i dont recomend swaping air files unless you know how to rebuild the aircraft cfg file.and stay away from aircraft the uses lots of textures cause one of those typs can drop your FPS down to 2 FPS thats another big reason to go with ai made aircraft.