Wireless N

Hi all, i have got an question, i have set up an link using rb800 and r52hn cards the link is about 6km, and has LoS, i am using 2 27dbi grids on both sides and arenusing both chains on the cards. My signal is about -53 and quality of 70/80%. bandwith test only shows about 45mbs, is that the best i can do? I get packet loss when trying to ping the internet when there is no traffic passing through the link. My signal to noise is 60dbm, is that good? Noise floor is about -107. i am running nstreme but not nv2. Help please