I'm new to eclipse's and wondering what aftermarket stuff to go with for a mild lowering of the car it is a 99rs also how would I go about converting the rear brakes from drum to disc

Welcome!

As far as mild lowering, you want to stick with name brand is the biggest part. Your whole car and the safety of others rides on them. Id stick with Eibach, Tein, Megan, etc. for lowering springs. Of course pair then with new shocks (Tokico HP are a good budget for mild lowering). And dont forget the camber issue.

As for the brakes, here is a wiki article: http://www.2gnt.com/index.php?d=Rear_Drum_to_Disc_Conversion

If you go the home page (2gnt.com) and click on Cars, then maintenance and modifications you can drill down through there and find what you need, as well as learn a ton.

Thanks!

Thanks a lot if you have any more detailed as for exactly what all I would need that would be greatly appreciated thanks