Anyone with a car older than 15 years or so likely has a coolant expansion tank with the structural integrity of wet toilet paper. These tanks rarely get aesthetic love in the factory vehicle design. They are usually plastic, look weird and can start cracking given enough time. After 20 years, the expansion tank in my 1995 Nissan 240SX project car will literally begin crumbling around your finger if any sort of pressure is applied. We don't want that happening to your RS/ST a decade or two from now, so we decided to design a sweet looking expansion tank that will outlast the car and be a nice addition to your engine bay.

The stock cap on the RS has a pressure limit of 21psi