Short research says it drops compression on stock block gsr. Think about it, usdm block isnt very high compression pistons. Like i said though, it does have future potential and if he wants to give him head (giggity), whos to argue but costs incurred just to use it immediately arent worth it. If its gonna be suggested should at least advise a game plan with it. Build schemes should be more like packages and not snap on lego pieces. Not all parts benefit from a drop in.