The cylinders I have are Mahle, 98 mm. the pistons are RUF. I bought these from an individual that had installed them and then decided to go even bigger. I do not know the source, but you could try the Mahle or Ruf web sites. I emailed RUF when I first bought the set, and did get back some additional information on the P & C's .
http://www.mahle.com/
http://www.ruf-automobile.de/
Vic