My upload speed never goes above 350 KB/s. I have cable broadband and wifi from an old desktop pc, but incoming can get 2000 KB/s, can I please increase my out going to share more ? Thanks in advance..

Read Optimizing Tixati help guide.

ISP bandwidth limits are often asynchronous, providing a much higher download rate than the upload rate.
do a direct bandwidth test on sites like:
 http://www.dslreports.com/speedtest