Not necessarily. In fact, Gamo had a couple of pretty good reasons for using that "scrawny" tophat and spacer I believe. Depending on the tune, for the past several years, I have often replaced the heavy tophat with a lighter one and then pushed the spring. I think they figured out what I (and I think a couple of other pro-tuners) was doing....lol... and why and the difference it made in some applications. Believe it or not, they do watch what goes on with interest in given areas. In fact, Gamo USA has contacted me a couple times in the past couple of years about some things that they had an interest in.
Anyhow, a lot of guys out there believe that by using a heavy tophat that the power/velocity is increased and in many cases it might be so but at the same time, at the expense of efficiency. Most pro-tuners machine their own custom fitted tophats and depending on the weight and spacing that they want for a particular spring application. The ones that I custom make I either drill them out or machine the difference in height or weight or both to accomplish the end result that I want for a particular gun. There have been times that I have eliminated the weight entirely and made a tophat out of Delrin for certain applications.