FYI: Your download speed is relative to your upload speed for any given overhead that is necessary. eg: downloading a file requires a small amount of extra upload bandwidth to communicate with the network and any uploading hosts which you may be downloading from.

Perhaps you may want to look into lowering your upload bandwidth by 10-15% to maximise your download speed. (85-90% overall upload bandwidth is all you will need to appease the download->upload overhead.)