As the title suggests, I was just wondering if anyone could shed some light on the difference between these two valves for me. They look exactly the same to me, but obviously have some sort of difference to have different names? Are they for different models of car or something? It's just I have been told that an N75J valve would be a good idea to have on my 2000 plate S3, although I've come across a few N75H valves that advertise themselves as 'Race Valve'. Cheers, Sean.