Cometics by far. Locwires gave me trouble with the big bore and combustion chambers of the stage II heads. Plus with the cometics I can specify thickness to play with compression ratio or make up for a milled head. Priced about the same as a locwire set for normal thickness. On the high dollar pro 5.0 mustangs locally the Cometics are performing perfectly, versus the 5 or 6 pass copper gaskets they had been using. No down side to them. Still would not recommend on a stock block motor, I prefer the head gasket to be the "fuse" on those motors.
Greg Kring
9.05@150 street car