My guess is that @kuntaltest has the R1 revision of the router ( the one from the russian ISP with custom firmware as in the
http://forums.dlink.com/index.php?topic=75107.0 thread ); that one did indeed had an embedded torrent client and also telnet access enabled if I remember correctly ( 2 features I would like to see in the global/US versions of firmware also).
@kuntaltest could you also please tell us the download speeds you get from the native torrent client when writing to the USB HDD ; also could you test the read/write speed to the attached USB HDD from your internal LAN ( copy a large file to and from that HDD ) . These answers would help us identify an issue with the USB storage performance on the US/Global versions of the router ( rev A1 ) where most of the time it maxes out at ~ 7 MB/s .
If you're getting consistent higher speeds then it's a software bug and not a hardware limitation ( the CPU+RAM combo should be good for at least 15-20 MB/s as possible in other similar routers and indeed occasionally it reaches ~30 MB/s transffer speeds for me but only on a time limited basis )