What type of metal are the charge pipes, namely the one to the throttle body, made of? What type of metal flange should be welded onto the pipe for a BOV?

Also, recommendation for BOV's and kits?

the factory pipe to the throttle body is just plain steel. When Jimmy bought his BOV it came with an aluminum flange. A guy at work made me a steel one for hime. Its identical to the aluminum one.
Tim

Thanks! I didn't know it was steel, it seemed kinda thin for steel. Thanks again!