Well what you could do is ring your insurence acency... and ask if it would that would be the simplest way.... I had mine lowered and it didn't change mine monthly rate... im with SGIC... But not sure how good it is im prob getting gypt, and also cause im a p plater.. i pay 38 a month.
well i dont know much bout insurance companies with lowering but i just lowered mi car today and it cost me... $193 - 4 Vorelli Sports Low Springs (trade order brand new!!yewl) $222 - 2 front gabriel struts, 2 gabriel rear lowered back shockies $229 - to fit the above^^ $40 - wheel alignment TOTAL~ $684 also i need to bend mi rear tyre guards cos their scraping the tyres! :-( devo!
i did lowering the cheap way and it still cost me round $700!
hope this helps if u WERE wanting quotes lol ;-) p.