In a stock machine without any mods,I do not think that this tensioner is needed. If you have a full on big bore, special camshaft, pipes, and bigger carbs, ie: a street hot rod or roadracer, you could use it...but one has to be very carefull when adjusting, I do not use these and they are not to be used with our M3 slipper tensioners.
Trying to adjust while engine is running would be a great mistake.
They are not needed, in my way of thinking, but they do look nice and are well made. Be prepared for problems unless you have a lot of experience in tuning these engines.
KOS