Combine 1 3/4 cups flour, butter and sugar in a bowl. Beat at medium speed, scraping the bowl often, until mixture resembles coarse crumbs. Stir in 1/3 cup mac nuts.
Press crust mixture evenly onto bottom of ungreased 13x9-inch baking pan. Bake for 18-22 minutes or until the edges are very light golden brown.
Combine brown sugar, 6 tablespoons flour, and salt in a large bowl; whisk until mixed.
Add Lilikoi syrup and eggs; mix well. Stir in 1 1/2 cups chopped mac nuts.
Spread Lilikoi mixture evenly over hot, partially baked crust.
Bake 30-35 minutes or until the filling is set and a knife inserted 1-inch from the edge comes out clean.