Phaser Scale Polygons

    loadPolygon: function (key, object, scaleX, scaleY) {
        if(scaleX === null)
            scaleX = 1;
        if(scaleY === null)
            scaleY = 1;
        if (key === null)
        {
            var data = object;
        }
        else
        {
            var data = this.game.cache.getPhysicsData(key, object);
        }

        //  We've multiple Convex shapes, they should be CCW automatically
        var cm = p2.vec2.create();

        for (var i = 0; i < data.length; i++)
        {
            var vertices = [];

            for (var s = 0; s < data[i].shape.length; s += 2)
            {
                if(scaleY < 0)
                    vertices.push([  this.world.pxmi((1 - data[i].shape[s] * scaleX)), this.world.pxmi(data[i].shape[s + 1] * scaleX) ]);
                else
                    vertices.push([this.world.pxmi(data[i].shape[s] * scaleX ), this.world.pxmi(data[i].shape[s + 1] * scaleX) ]);
            }
            if(scaleY < 0)
                vertices.reverse();

            var c = new p2.Convex({ vertices: vertices });

            // Move all vertices so its center of mass is in the local center of the convex
            for (var j = 0; j !== c.vertices.length; j++)
            {
                var v = c.vertices[j];
                p2.vec2.sub(v, v, c.centerOfMass);

            }

            p2.vec2.scale(cm, c.centerOfMass, 1);

            cm[0] -= this.world.pxmi(this.sprite.width / 2);
            cm[1] -= this.world.pxmi(this.sprite.height / 2);

            c.updateTriangles();
            c.updateCenterOfMass();
            c.updateBoundingRadius();

            this.data.addShape(c, cm);
        }

        this.data.aabbNeedsUpdate = true;
        this.shapeChanged();

        return true;

    }

};

Replace the default loadPolygon in Phaser with this class.