Vauxhall Vectra 2.5 v6

hi there i recently brought a gsi ... i thought but turns out to be an sri v6 , so can any one tell me the difference compared to the gsi ? my sri seems to have had a gsi kit put on it with door badges , ive put the phase two 17" alloys on there , also the seats are the same bar recaro stitching is there anything else different? . also i want to drop this about 20mm ive heard with gsi the shocks are different to sri ? so what springs do i get or is there a website that shows pics any ideas