I am replacing CV axles on an 09 Porsche Cayenne GTS because of a torn boot, and ended up having to use a pickle fork to separate the ball joints (screw type separator was mushrooming the stud), which ended up tearing the ball joint boots.  The ball joints and control arm bushings are in great shape - I just need to replace the boots as I put things back together.  However, Porsche does not sell ball joint boots (they want me to buy the entire control arm), and I can't find third party boots that look anything like the originals.  The original boots have rings around the top and bottom to hold in the grease, and are bellows design - everything I have found at auto stores does not use rings, nor are they bellows design - and I'm concerned that using these "universal" boots won't hold the grease.  I'd prefer to replace the originals with heavy duty polyurethane ones, but right now any ones that will fit are OK by me.  Seems to me that someone, somewhere is making ball joint boots that can be substituted in.