This paper proposes loss budget improvement of the bus-type optical access network (NW) with cost-effective non-repeater configuration. To achieve drastic improvements, we propose two approaches; (i) application of a low noise distributed Raman amplification (DRA) technique to upstream signal transmission (ii) utilization of asymmetric power splitters at each drop point to enhance Raman gain and to suppress transmission loss of far branches. We optimize the asymmetric power splitter drop ratio to maximize the number of accommodated users. Then, we clarify the number of accommodated users and improvements based on DRA through calculations that examine the inter-drop distance and total branch number. Experiments evaluate the bit error rate performance of the proposal. We confirm that measured values correspond to the simulation results. Based on the simulation and the experiment, we clarify the optimal network configuration for the user distribution. It is found that bus-type NWs support more accommodated users with shorter total fiber length than star-type NWs for user range examined. The potential advantage of bus-type NWs is revealed.