Tell rsync to compress in parallel

Is there a way to tell rsync to do compression in parallel, eg. with pbzip2? I am trying to speed up our overnight backup. Our Rsync with compression currently has a bit rate

sent 1705628134 bytes  received 19432 bytes  3076010.04 bytes/sec
total size is 8064769536  speedup is 4.73

      

        
        
        
      

    

while one cpu core is 99% and the network allows 55-60 Mbps, which is apparently more than the actual 8 * 3 Mbps. We have Oracle Linux 6.5 with

rsync.x86_64                           3.0.6-9.el6_4.1