Wheel weight and unsprung weight info
some info that may be useful within a realistic budget
oem rs6 7.5x18 et54 weigh 12.9kg
oem s3 7.5x18 et52? 12.5kg
bbs ch 8x18 et50 10.9kg
bbs ch 8x19 et50 11.5kg
reps rs6 8x18 et46 12.4kg (special soft and bendy version)
ultraleggeras 8x18 et45 8.4kg
race pro 1.2 8x18 et52 8.9kg custom made
mtm 9x19 are 16.5kg for comparison
i ignored the silly priced ultra light ones - such as folk etc etc which are generally £400-£600 per wheel
i just swapped my oem rs6 for race pro 1.2 so lost 4kg per wheel - does it make a difference? surprisingly yes it does. there is less crash on bumps, the steering feels tighter and more precise with better turn-in, slightly lighter steering and the whole car feels much more nimble on the b-roads particularly.
im not sure that oem to bbs 12.9kg to 10.9kg would be as noticable but then most people upgrade for the looks not performance... however bbs will cost you £1100-1200 where as race pro 1.2 can be had for £500-600 a set.
other useful unspring weight savings can be had:
1) s3/r32/3.2 front brakes have alloy calipers and are much lighter then the steel standards
2) tt alloy front bottom arms are lighter and give the much needed negative camber
3) s3 hubs are alloy and save a few kg each wheel and are quite cheap.