Core Stateless Fair Queueing (CSFQ) is a scalable mechanism to provide per-flow fairness in high-speed networks in that it does not need to maintain per-flow state in the core routers. This is possible because the state for each flow is encoded as special labels inside each packet. In this paper, we propose and evaluate by simulations two improvements to CSFQ. First, we show that CSFQ does not provide a fair service when some links are not congested. Our first improvement solves this issue. Second, we propose an algorithm to allow CSFQ to provide a service with a minimum guaranteed bandwidth and evaluate its performance with TCP traffic.