Any N rated routers have a 'claimed speed of 300mbps' In the real world throughput you can expect about 150mbps. This is due to wireless routers being half-duplex, which means you can only transmit or receive not both at the same time.
However the speed with depend greatly on a number of factors, (walls, doors, metal objects, distance, etc...) All and all, you will be lucky to get sustained Wireless G speeds.