To increase the braking power of your brakes you have a few alternatives: if the pads are in good condition and the oil was recently changed the discs might be "tired" or they are undersized for the their use. From designs, colors and materials there is a wide selection of replacement discs brakes to improve the performance of your bike. Those focusing on the effectiveness will appreciate the Shimano discs with Ice Technology or "Freeza" profile, the ultimate as far as pure performance. Those looking for lightness at all costs could try out the Discs from Ashima consisting of 2 pieces.