The combustion chambers involving the engines are quite diverse regarding their squish space. Although their valve sizing and position are identical the Silvertop contains a chamber that has a squish region in every single hole in between the valves. They don't seem to be a thing that needs altering as https://4age-20v-turbo-engine-for05815.blogunteer.com/31341047/detailed-notes-on-4age-20v-itb