I did wonder if it would make any difference at all but I genuinely feel it has helped the car massively through faster corners. Example 1:
Turn 1 at Rockingham... flat in the car without the wing but the car moved about a bit mid corner and never felt 100% stable, now though with the wing its easy flat and the car feels much more planted and easy to control. Just keep it pinned and make one movement on the steering wheel.
Example 2... and this is the one that convinced me it is working, flat through Craner Curves at Donington. I've driven the corner plenty of times without the wing and never really had the confidence to go flat out at the left hander, did a couple of sessions a few weeks ago and built myself up to being able to take it flat out, the wing really is helping keep the rear of the car settled in the higher speed corners. It felt nice and planted turning in and I was able to push hard through the craners and fly through the old hairpin.
Its just a shame I dont have any lap time comparisons to check if its making the times faster but, from behind the wheel it feels better.
It just need to sort the new engine out now!