Duplication

I need some help.

My environment.

WS 2008

NBU 7.6.1

1> I am trying to duplicate my old LTO1/LTO2 tapes to new LTO4 Tapes but I am getting a very low throuput of 20 mb/sec. I have LTO3 and LTO4 tapes reading the LTO1 and LTO2 respectively.

Is this the max we can get or we cam improve the performance by any tweaks.

2> Also how to find if I am utilizing my LTO4 at full. How to check the throuput on my LTO 4 and best utilize them in duplication.