Facts

Although GreedyTorrent can be configured to give any multiple of your actual values, its generally not recommended to use values higher than 1.5 or 2 times your download. Multiples of actual upload are recommended to that of download. Higher values are likely to result in detection than smaller ones. So use the software at your own risk, only you are to be blamed if you get a ban!

While not recommended, one can stop the torrent file and keep it from seeding once you complete download. As GreedyTorrent takes care to maintain the fair ratio you specified automatically as you download the file, you do not need to seed it further to keep the ratios high at the tracker. However, this would ruin the efficiency of bittorrent protocol as higher number of seeds is what makes it efficient. So if you have good upload bandwidth, be fair and set the ratio to be a multiple of upload and seed the maximum amount possible.

Only the upload ratio reported to the tracker is modified. The upload value your bittorrent client displays is the actual quantity you uploaded, and it remains the same.