None specifically, but if you're looking for a tuning box, enquire to any of the TDI tuning box vendor outlets like Van Aaken, etc. A similar result can be achieved very cheaply via the "Evry mod". It should apply just the same to the SDI as on the TDI. Read up on the subject in the performance forums in a thread entitled "Chapagne [sic] performance on a beer budget." Be forewarned however, that going too far will result in a VERY smoky exhaust.
As for chip tuners, those available in the UK include Superchips, AmD, Wetterauer and a host of others. At best you can expect maybe 5-8 HP from tuning an SDI via a chip or box alone. Anything more will mean smoke out the tailpipe.
More traditional power enhancements like improved induction (head work, exhaust, intake, camshaft, etc.) will benefit an SDI just the same as any other normally aspirated engine, but to realise an increase in HP, you need to increase fuelling simultaneously.
Do a search on Google using "tuning VW SDI" as the keywords. One vender in France has a chip that claims to raise the HP in a Polo 1.9 SDI from 64-72.