The thing is though that there are Clio turbos used on track which will be hotter on the IAT side of things and therefore put more heat into the engine but have no issues.
That's why I'm asking about the IAT, because then you will at least know how much heat is going in. If they aren't that high then it's another issue.
That's a good point, but the intake now come's from directly behind the headlight and it's got a pretty big intercooler, so I don't see how I can get the intake temps any cooler. I am 99% sure it's another issue.
Have you checked the thermostat? Sounds stupid but it's sometimes easy to overlook the simple things. Also I'd consider putting a shroud around the rad to duct the air through the rad. Otherwise it'll just spill around it as it takes the path of least resistance.
Bigash had similar cooling issues with his, but at the time he wasn't running a stat so the engine was just one big kettle effectively. He fitted a stat and shrouded the rad on my recommendation and he didn't have issues again.
Not stupid at all mate, sometimes the simple things can catch us out, but yes I have checked the stat and it's fine. I did consider removing it but have read that this often causes more problems as you have pointed out.
A shroud around the rad is not a bad shout either. I have also considered a more powerful fan but doubt this will have any benefit once out on track.