Sprints had a similar problem with soft lever feel and increasing level travel. Whoever asked about the cleaner. The brand out here is Brakekleen about $10 a spray can that lasts about 12months. Hope this is useful, one thing I'm glad about the 07 S3's don't have this problem.
Here's my reply from TRAT Sprint forum: Assuming it won't get me banned here's a link to the thread: Sprint Brake thread
Copy of my posting from the thread below:
Firstly CLB, the change in travel is NOT due to wear. You can fix the problem by cleaning the caliper pistons there is no need to bleed the breaks. I had a 05/06 Sprint that had this problem and I bought a spary of brake cleaner. Each "clean" lasted about 2000km before feel went "off" and travel increased markedly. I then coated the pistons with rubber grease and this lasted about 6000km before the feel went off. Over about the 5 times I did the different fixes, I only bled the brakes once.
Here's the forum topic that discussed this last year
The following is the "cleaning fix" from that thread:
"1) Undo both bolts on 1 front caliper
2) Remove from disk/fork
3) ***Lightly*** squeeze the front brake lever until some of the "clean" metal of the piston barrel is showing.
4) Spray with "brakeclean" (top and bottom)
5) Use a medium flat blade screwdriver to open the pads/return the pistons
6) Refit caliper to fork/disk
7) Pump lever until firm/hard to get rid of sponginess from opening the pad gap
8) Repeat steps 1 to 7 for other caliper for Jap bike style firm lever action
9) Repeat 1 to 8 every few thousand Kms as necessary.
I did this at 2700KM, so I'm hoping it's not that often, around 5000KM when I do an oil change would be fine as you can do this while the oil drains from the sump.
This took all of 10mins including find sockets and screwdrivers to do the job.
I went for a 150KM rid this afternoon and had the brake lever set on position 2 and the brakes were great.
When I cleaned them the spray dissovled and removed a significant amount of gunk that looked like brake pad dust. It seems to be sticking to the pistons, preventing them from returning against the seals, giving a very spongy feely. Cleaning removes the gunk and the pistons return when the lever is released and the seals retract leaving you with a nice firm action feel."