"Got 1980 450SL for 18th Bday, what can I improve?"

Your Income. Did I get the answer right?

Seriously, you will find that parts for an SL are more expensive than a sedan or lower end Mercedes. So you should start fixing what definitely needs fixed first (such as a leaky top) before working on cosmetic items. Pace yourself on the repairs. It doesn't take long to dump a lot of money into one of these cars. I don't know how easy it will be in Austria, but for the USA SL's, most parts are available from the Mercedes dealer, and many private parts sources, if you have the cash.

Here's my opinions:

1. If the roof has a lot of holes, but you just want to keep the rain out, have it patched. If you want to do it right, have it look like new, and have the money, get a new top and have it professionally installed.

2. Stereo system: replace it. New stereos are much much better than the original, and you can get a good one for not much cash. Keep your old one, and don't hack at the original wiring, in case you want to ever restore the car to original condition.

3. The chrome comes in three variants: Chrome plated metal, polished alumimum, and chromed plated plastic (plus some stainless steel). The chrome plated metal can be polished up or rechromed. The polished aluminum is very hard to shine back up (so some seaches on the site for more info), and would be easier to replace. The chrome plated plastic should just be replaced. The stainless can be refurbished with the right knowledge. But of course any replacement add cost.

4. Wind stoppers: I know they exist and have seen them here in the US, but that's about all I know. They mount behind the seats with no permanent modifications from what I hear.

My $0.02.

Have fun with your new toy.