The Go's come with one aluminum and 2 brass shims. If you added a third brass shim for break in you can take it out after break in. You could also take out another brass shim so you only have one aluminum and one brass. Go's seem to have more clearance than a Novarossi, just be careful to keep an eye on temps and too much compression can blow plugs. If you blow plugs then put the shim back but I don't think you would have any problems.

Rex