Various pieces are available in fiberglass, but they may be better suited to more pure race cars than something you want to drive on the street.
You can strip various interior pieces. You can also run aluminum heads, wheels, intakes, etc for weight savings. Every little bit helps. Heads ain't light, neither are stock intakes. Headers may also be lighter than exhaust manifolds. You can even get carbon fiber driveshafts that are pretty light. You could even look at replacing the rear end for a lighter unit or even some custom aftermarket pieces that weigh less.
You can strip various interior pieces. You can also run aluminum heads, wheels, intakes, etc for weight savings. Every little bit helps. Heads ain't light, neither are stock intakes. Headers may also be lighter than exhaust manifolds. You can even get carbon fiber driveshafts that are pretty light. You could even look at replacing the rear end for a lighter unit or even some custom aftermarket pieces that weigh less.