Depends were in Austria. I lived in southern Austria for just over 7 years. I ran a biker hotel so we had lots of experience of their interaction with local police. In Carinthia the police are mostly pro bikes, yes you will be stopped and fined if you speed in the towns or ride like a twat, but generally they are fairly laid back. We have personal experience that this is not the case in all of Austria. Police in the Tirol are far harder on bikes in particular and I have heard stories of people being fined for using HID lights. Where I lived you were extremely unlikely to be stopped by the police unless they caught you speeding so as long as your lights aren't obviously blinding to others I don't think you would have a problem.
For all the time I was in Austria my bike had an illegal exhaust in that I removed the cat. (fitting it back once a year for testing). As it was an Austrian registered bike a cat. is a legal requirement. On an 1150 GS the fact the cat. is missing is obvious but I never had a problem. Even in Carinthia they do have some standards about noisy exhaust though. Every year they pull a few Harleys at the annual Faak am See meeting. Those will be the ones with just a couple of inches of pipe sticking out from the heads!
The first thing you have to remember is that an Austrian Policeman (or woman) has far far more discretion as regards fines etc than our UK forces do. We had several cases of people "talking up" a speeding fine by arguing with the policemen. Austrian authorities, at all levels, are used to being obeyed and certainly not questioned. They react badly to such things and we have heard of fines being doubled or more in response to an argument. If you get stopped, switch the bike off, get off and remove your helmet. Be polite, even eat a bit of humble pie.
In my last summer there we only heard of one speeding fine in Carinthia over 25 Euros. Turns out that if you ignore a policeman waving you down and they send a car after you, you get fined 180 Euros!
Don't speed in the towns or ride like a twat (leave that to the locals!) make sure your lights don't cause others problems and you should be fine. Oh and just buy the Austrian motorway vignette, it's just over 5 Euros for ten days. Leaves your options open to just use an Autobahn when that makes sense (avoiding large towns for instance)
John