^this. Pick a lower number to start. The entire OS table should be that number (5, for example). Copy your spark table and do a paste special-> add to the OS table. This will make the OS table exactly the same as the spark table with every cell being 5 higher than the spark table. That's how you want to set it up as a difference table. Conversely, if you subtracted the spark table from the OS, you should have a difference of 5 left in each cell (the entire OS table will be blue and every cell will be 5) if you've done it correctly.
On a side note, I've tested as high as 50 in certain cells. 50 appears to be the limit of stability for the ecu. It's WAY WAY too high. I just experimented to find the limits of urgency. It's like requesting a car go from 0-150mph instantly. Even with 2000hp the car may try, but your drivetrain is going bye bye. Not physically possible.