Stay away from aluminum A-arms and stick with RPM brand. Rpm is made of a very durable nylon material that flexes instead of breaking under stress like plastic. Aluminum bends and stays bent. You can go with aluminum bumpers with stock plastic mounts and aluminum bulkheads and chassis braces. The stock plastic bumper mounts will leave a flexing point between bumpers and bulkheads. Aluminum shock towers are also a good choice with the stock plastic body post. RPM just released their new tmaxx bulkheads and I'm sure it will be a good product to try vs aluminum also. Whatever you do for aluminum stay away from INTEGY brand. An aluminum beer can has more structural integrity. Stick with GPM, HOT RACING, FLM and any other quality brand of aluminum.