Just installed these on my 1992. They seem to be slightly better than ok quality. When opening they are fine and move quite freely but when closing they catch a little bit and aren’t as fluid.
The hinge they mount to on the bonnet is fairly sturdy so I do see them lasting quite a while and they fit nicely under the bonnet. They do definitely raise the bonnet slightly around the hinges though so if you like your panel gaps nice and tight I don’t think these are for you.
Good honest writeup 
I had these for a while on my old mk1, just like you I noticed they raised the bonnet slightly. Over time the forces started bending the bonnet hinges until the back of the bonnet always looked like it was fitted badly. I think the design of these put too much leverage on the bonnet hinges, they act like a big fulcrum flexing the hinge so I won’t be using them again.
A lot of people fit them because the original stay won’t fit due to engine modifications, but it’s far easy to bend a bonnet stay around your supercharger than it is to fix twisted hinges!
Just for clarity’s sake this applies to all aftermarket gas strut bonnet lifters that are of the same design, not just the IL Motorsport ones.
Over time, the NA bonnet hinges seize up, making them all appear to fit badly. Whether or not these struts accelerate this is another matter.
Also not all gas struts are equal.
I agree the usual NA fitting scheme seems to stress the hinges unduly. The NC fitment less so but the flimsy ali bonnet can bend!
I found the gas struts in the IL kit I bought from our sponsors above were much too strong for my NC’s ali bonnet and replaced the struts with gentler ones made in UK, but I kept the IL mounting brackets etc. As shown below.