In the Porsche world a well regarded alternative is to have Bilstein rebuild the existing units. I believe there are two Bilstein rebuild locations here in the US...East and West. There are also independent, certified rebuilders as well. You might want to reach out to the UK rep below or contact the German headquarters and inquire. Good luck.
UK:ThyssenKrupp Bilstein Technical Centre UK for Special Projects and
Damper ServiceUNIT 3, Swannington Road, Broughton Astley, Leicester
Leicestershire LE9 6TU
United Kingdom
Tel.: 0044 01455 288410 for special projects, 0044 01455 283407 service work
Fax.: 0044 01455 283301
E-Mail:
richard.anderson@kruppbilstein.co.ukGermany:Standard replacement, customising, amateur motor sports
ThyssenKrupp Bilstein Tuning GmbH
Milsper Straße 214
58256 Ennepetal
Germany
Tel.: +49 (0) 23 33 / 7 91-4444
Fax: +49 (0) 23 33 / 7 91-4400
E-mail:
info@bilstein.deBelow is what is offered here in the US:
(
http://www.bilsteinus.com/services.php )