Janspeed do do eom - a s/s and a mild stell. Ashley only do mild steel. I would refrain from m/s as they don't last too long - my mate had 2 Ashley m/s ones in 3 yrs on his MFi

I had a s/s Magnex on mine and it was truly the nuts. Superb fit, quality was amazing and perked the engine up more than expected. Sounded wicked too