What range of tcp buffer size do you suggest for slow and fast networks?

If you search the net, you come across with ranges like these that claim would enhance your net throughput: net.tcp.buffersize.default=4096,87380,256960,4096, 16384,256960 net.tcp.buffersize.wifi=4096,87380,256960,4096,163 84,256960 net.tcp.buffersize.umts=4096,87380,256960,4096,163 84,256960 net.tcp.buffersize.gprs=4096,87380,256960,4096,163 84,256960 net.tcp.buffersize.edge=4096,87380,256960,4096,163 84,256960 In place that I live, the net speed of gprs/edge connectivity is so slow that even sending just a sentence of text via instant messaging apps like Whatsapp could take up to 5 seconds and even fails to send some times! but on the other hand my wifi connectivity is very fast; so; what range of tcp net buffer size do you recommend for these two connections that better suits me?(or maybe any other effective variable)