The dual conical springs have less friction than the K950 springs that were on there before so that means they will free up some power. It might be too small to measure on the dyno, or it might just get swamped by the other factors. But even if the friction is too small to be measured on the dyno you can see the result on the valve spring with all of the worn shiny areas. Of course, people have been using the interference fit dual spring for 50+ years so it isn't like they are a really bad design. Just something to consider.