Depends....
If the ISP just filters or capps connection/speed on the usual filesharing ports (for Gnutella it's 6346) then you can avoid it by simply using other ports to connect.

But there are also some ISPs using protocol filters which analyse and filter the traffic for specific key words like GNUTELLA CONNECT
which is the handshake of Gnutella.

I think Sandvine has a filtering and monitoring app for Gnutella..