JBA's come in 3 stainless steel versions coated SS headers and work better than mild steel. stainless does not transfer heat very well, so the engine compartment stays cooler. This slightly increases power, saves wire insulation and hoses from rapid deterioration. one problem with plain steel headers is a progressive drop in power as time goes on. big cause of this is having the inside of the pipes rust, which roughens the pipe walls and changes exhaust gas speeds. On a dyno a lost 50 bhp from rusty headers, and gained it back on dyno runs by putting on a new set of the same pipes.
Ron