Facom Roller Type Stud Driver/Extractor - 8mm (287B.8) - the 287 Series are the best and most compact stud extractors I've ever used. Great for removing and installing studs, even in tight spaces. Studs are gripped in either direction by 3 sets of rollers (see photo) . 1/2" drive for plenty of torque.

This is a popular size for European cylinder head to manifold studs.