I added the over flow reservoir to my 300D and it works fine (no coolant loss). I found some open space and tie wrapped the reservoir securely (I did not drill the body). I have done this for the last 20 years to several of my cars and have been very happy with it. Go to your local auto shop (Grand Auto, Kragen etc.) and purchase a radiator over flow reservoir (less than $10.) and install it. Make the laws of physics work for you not against you!