On torrents, that depends on a TON of factors, the most important of which, you can't see.
Your speeds aren't based solely on what your speed is, or even what their speed is. Believe it or not, your router can totally effect torrent speeds. A cheap router can only handle so many connections, and the tor network can flood out even good routers very, very fast.
What you think is overhead, isn't the overhead you need to be concerned with. There is overhead, as in how much data is sent for negotiations, which can easily be measured and seen in the client, that's easy, but what you can't see is the number of operations to handle them. If you say it can use a max of 200 connections, you will have 200 connections of data coming through your router, on top of anything else you are doing. Even a good router can choke much above 200 connections, because while you have 200 connections, each connection can generate a ton of back and forth traffic, it has to ask for data, get confirmation, send data, say it got it, then verify it, then do it all again. All that, per chunk of data, per connection, it can quickly add up to thousands of simultaneous operations. While 200 connections sounds low, it's enough to nearly drown a router with 64megs of ram. 64megs of ram, is a high end router. Your modem router combo, that you got free or cheap, will almost certainly have less than that.
Basically, you will never see max speeds on torrents, ESPECIALLY with a cheap router, even after you tune it, and account for overhead, there is just too many I/O operations for it to happen. This is also why you will never see max speed in each direction, the more going out, the fewer you can have coming in.
