The composite gasket is usually the "no-retorque" type, which saves a little time during engine assembly. The solid copper or steel gasket needs to be torqued again after the engine warms up. On the very high compression race engines I build, a solid gasket is an absolute necessity when the compression ratio gets above about 10:1, and the blower engines use a stainless steel O ring to seal compression, and a copper shim gasket to prevent water leaks. Unless you're going for extreme perfrmance, the composite gasket should work fine for street use.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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