The bling Cosworth radiator cap I got is leaking with my Mishimoto radiator :( There was no leak with my 5+ year old well used Nismo radiator cap. I can confirm this with extensive testing. Excellent quality and durability for the Nismo but so much for the famed Cosworth quality. Anybody interested to further test the Cosworth radiator cap can contact me. Anybody interested in my old Nismo radiator cap can also contact me. I can guarantee it (the Nismo radiator cap) still has at least a couple more years of useful service life.
I ordered a new Nismo radiator cap from RHD Japan which arrived in less than a week. Picture below of me radiator cap installed. Unfortunately the "Nismo" logo and warning text on the radiator cap label do not appear horizontally aligned with the Mishi radiator. WTF! Same problem with the Cosworth. There is no alignment issue when the Mishi radiator cap is used.
You can read up on Nismo radiator cap details in my old post here.