As Scarecrow said, the luff looks very loose.

Spi also looks like it have a lot of draft with the current setup. With a more tight luff this would change, but your leech does not look like you can increase the hoist too much.

How is your helm when sailing downwind with spi?
Did you change your mast rake when setting up for spi?
What type of boat did the spi come off, and how old is it?