i work on a lot of sites, got they top 10. but i do not know something between rank they. commonly, I add some good backlinks and big boost some keywords ,for example, from 100 to 50 which i targeted. but after weeks , usually with my site cache got update by google,almost all keyword got a huge boost ,for example, from 100 to 50 , some from 300 to 60. does it happen to you? i think it is because google trust you ,and boost your site. what do you think of ?
when u got boost in ranking only one factor is not important, there are thousand of factor which affect your ranking. as u told u bode mass link exchange but u had done some changes on site.which also affect the ranking, and its happen to all the people.
It's usual to have good rankings when you have good backlinks to back up your site with proper optimization methods used..