Differences in gsxr 600 for year 04 thru 08

I am looking at suz gsxr 600 in years 2004-2008. Would love to have an 08 with low mileage that is too expensive. So I  see for sale an 08 low mileage for $6000 down to a '06 also with low mileage for $4,000.    MY Question is what are the differences through those years?  What changes happened from 05 to 08??? And how significant are the changes?  And would most riders notice a big difference in those 2 years  

'04 and '05 were the same, here is the press information for the '04 model:

http://www.sportrider.com/bikes/2004/146_04_suzuki_gsx_r600/index.html

'06 was a big update, with a new frame and the engine was all-new - earlier versions had cases with two splits, that was changed to one split and properly stacked transmission:

http://www.sportrider.com/bikes/146_2006_suzuki_gsx_r600/index.html

No changes for '07, '08 was a bunch of minor updates:

http://www.sportrider.com/bikes/146_0806_2008_suzuki_gsx_r600/index.html

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