I've played with a few different 802.11n routers. The only way to achieve a 270 or 300Mbps connection is to get a router that supports 5GHz wide band. I don't know if it's a hardware limitation or a driver restriction, but with Mac notebooks, you just can't take advantage of 2.4GHz wide band, so you'll never get more than 130Mbps.
I learned this the hard way. First, I got the Belkin N1 Vision, and then the D-Link DIR-655, which are both 2.4GHz routers, and I couldn't achieve more than 130Mbps.
At the time, all 5GHz routers were still expensive, so I ended getting the Apple AirPort Extreme and configured it for 5GHz wide band. All of my Macs can either connect at 270 or 300Mbps now. Don't expect to come close to seeing real world transfers at those speeds though. When I'm within a few feet of the router, I've seen speeds as high as 10MB/s, which is only 80Mbps. With a 2.4GHz connection, I think I was able to achieve only 6MB/s (48Mbps).