Not sure about overclocking your connection. The speed you have with your ISP is what ever they allow and the wiring will allow.
Mine here in HK is very quick and I usually end up host for games from teh US, Europe and Oz...
Sometimes it sucks as the Xbox slows a bit, but its usually not a prob till you get whinging Yanks on there with yellow connections.
If your the host and the only green connection they whinge and whine. Even had a "clan" all report me to xbox live. They call and I told them. The other guys got some sort of ban..