I have a mint NOS one of these in it's original box which I bought quite a few years ago to use on my Mk1 project. Engine is a 1310 overbored 1300GT with 276 cam and around 85bhp.
I'm not bothered about whether they achieve what they claim to do just whether it will provide adequate cooling - I only bought it as I thoght it looked quite nice and 'in period'