I've just read that this is one of the most heavily cut films by the BBFC, but reading the synopsis on Wikipedia, it doesn't sound particularly controversial. Anyone know anything else about this?

All I found was a reference to Nammavar being cut by 5 min 8 sec for violent content.

Movie creates a great awareness of AIDS and knowing Kamalji's style, he would have explained in detail how he got AIDS, so lot of that might have been removed.

Kamal usually get inspiration from hollywood and end up taking movies ahead of time. This is another one. This is the time AIDS just started getting its "popularity" in India. He should have waited another 5 years, as many people in censor board at that point may not have believed in AIDS itslef!