48KB/s is almost 10times more than 56kbps

I wouldnt recommend setting your max upload speed above 3KB/s or you'll be severely slowing your downloading.. The common setting for those on 56k is 2KB/s.

Also, you arent really on 56k. If you're in the US, the maximum possible speed is 53k, and even that is rare.. Most connections will tell you how fast you're really connected with a number such as this: Conected at 41000bps [meaning 41k].