How much does a stay sail really add?

[csandys]

I've got a 32 foot cutter. This year I removed the stay sail, boom and stay. Tacking my 135 genny through the slot between the front stay and stay sail stay is difficult. Removing it also frees up deck space. I like the looks of the cutter, but it is easier to sail without.

My question is, how much more speed does the stay sail add. I've only been out a couple of times without it, but not enough wind to get to hull speed.