One of the current and up to date emulation tool that works today is mRatio. mRatio is a free and easy to use BitTorrent emulator where it simply loads a torrent file and then simulate the downloading and uploading plus sending the data to the tracker ignoring the amount of seeders and leechers. No files will be downloaded nor uploaded and it does not use up any of your bandwidth.
As a test, we signed up a private BitTorrent tracker website and used mRatio to increase our upload ratio. After running it for a few minutes, stopping the download and refreshing the profile page shows a positive ratio even though I did not really upload any physical file to anyone.
Using mRatio is easy. Download, extract the RAR file and run mRatio.exe file. Click the Add Torrent Wizard button located at the left pane of the program and follow the wizard instructions which is loading the torrent file that you want to cheat, selecting the client emulation, setting the maximum upload and download speed, proxy, and start cheating.
Although it is easy to cheat the tracker and increase your upload ratio using mRatio, it can however be easily detected as well. mRatio continues to send reports to the tracker and what the tracker administrator can do to detect the cheating is by stop giving real peers to the cheater for a few hours. When they still receive reports after stop sending peers to the cheater, it is a definite sign that this user is using an emulator to increase their upload ratio.
Another thing to take note is this public version of mRatio does not come with the latest client files. Some tracker sites allow the member to only use the latest version of selected BitTorrent client. Using an older build or an unapproved version would cause the account to be banned. You can however request for the previous build in the mRatio forum.