All kind of backpressure coolers are always mounted under the body. Most of them have the function to cool the gasses and create some volume as a pressure chamber.

The pressure chamber is already in the tank cap so why not cool the gasses there? It is the best place where there is a lot of airflow for cooling and it looks cool

There is still a lot to do but it is going to look like it.

Briliant idea Roelof!!!Hope you have patented it so noone can steal it!!!

And there it is.

Hey, that looks VERY COOL