Carbies are dirty untuneable things. Bite the bullet and go for injection and you wont regret it. I did and am soooo happy with it.

Or take it to a VW place (There are two in Canberra that are good) or a carby place and have them check it out. But unless the carb has been set up for your application then it will use too much juice and run like a dog. If your lucky it will go a lot louder but not any faster and you also heat up your exhaust by putting too much fuel through the engine so the unburnt stuff gets burnt in the exhaust.