Spatzle: You obviously already know about geometry changes with lowering at the front, and of course, the rear matters not at all from that perspective. It depends on how many preparation points you can tolerate. At least in Canada, the Eibach setup with Bilsteiin SPs was a dealer installed option from VWC, and I have a variation on that theme (VR6 wagon springs to maintain front ride height) in my wife's street car. IMHO, a bit soft for DOT race tires, but would not be bad for genuine street tire class.
Two things you could consider: IF you want to lower the car, use the Audi TT front spindles to drop a bit but maintain correct geometry. Think seriously about replacing all of the rubber in suspension with something a bit stiffer (urethane or VW Motorsport rubber). If you are going for broke, do the darn coilovers with double adjustable dampers and start logging records of setup.
IMHO: pay great attention to camber (adjustment at front maybe camber plates if allowed, camber shims at rear), alignment in general but above all else dynamic camber from rim width contribution (hint: here is no such thing as cantilever slicks for solo). A G-tech pro may be your best friend for a year or two. I would be looking for the smallest diameter, widest and lightest wheel/tire setup you can run without getting clobbered by prep points.
A few years back when I still had some time to play (and before they outlawed karts in solo competition in Canada) we had a MkIV Jetta competitor (on Shine IIRC) who would drive their 1.8T car (chipped only) with whole family to an event, remove the child seats and put the race rubber from little trailer on the car, take a good shot at FTD unless the karts or F2000 cars were running (YES, he was often one of the top 3 door slammers in the REGION!!!), pack the whole family up, head to MacD's and drive 600kms home. The car has serious dual-use potential.
