We all know that there is a huge modding community for FSX. If you are not sure what a mod is let me tell you. Mod is short for modification. These are in essence free add-on aircraft. I will warn you that not all of them are good. Some may not be of good quality and may not even be finished. Some also cary viruses so be careful upon download. I am not responsible for any issues that you may encounter with any mod. Now that we have gotten past the boring part let me tell you about my most recent one. I installed the Just Flight Boeing 757. It is a wonderful aircraft of payware quality. Just Flight is a company that makes payware but they give away the 757 for free. It only comes with one livery but you can buy more if you want. It is a great aircraft. Almost everything works and all of the systems are simulated properly. The flying model also seems to be quite good. The aircraft looks very nice too. You may have frame rate issues with the aircraft though if you do not have a decent computer. It is more cpu/gpu intensive than the aircraft in FSX. I really like this aircraft as it even has an FMC that works compared to the stock aircraft in FSX. It is a super aircraft that you need to try for yourself.