Torrents are Peer to Peer technology, so when you are downloading something popular that is locally available in Excitel Network you get 20 Mbps Peering speed, but also you will download from External peers with 20 Mbps more, as you also have 20 Mbps Internet Speed.
This way Speeds are combined and you can get total 40 Mbps speed on single torrent. Sometimes the Bittorrent Client software (utorrent) is smart and if it detects FAST Local Peers (in Peering) then it doesn't utilize the Internet Speed and only downloads from Peering as it might only need 2-3 Local Peers to get the Max speed, whereas from External Peers it might need to connect 20-30 to get max speed.
so what can i do to make sure that i get full 20 ( from internal peering ) + 20 ( from external seeds ) ? i have tried it a lot of times . downloaded well seeded top search list torrents. my speeds just hover b/w 20-25 mbps. it never goes beyond that.