i would recomend it, it wont hurt to stiffen the flow a little,and wont hurt your altenator as bad,trying to keep chargingmore than usual.hope this helps.
Umm if you already have one then you might as well use it however dont go go out and buy one. Save your money for an alternator, that is if you need one.
the words "need" and "stiffening cap" should RARELY (if ever) be spoken in the same breath. If you believe you NEED a cap - you problably really need a better alternator.
VW H/O alts are impossible to find. It took me 4 months before someone finally led me to a guy in Canada that specially makes alt's. If you are ever in need, his e-mail is vvanoverdyk@shaw.ca I just ordered mine today -- for a 97 Jetta GT.