well....can I just use coilovers on the stock springs to lower the car to look good with the 18s? and whats the proper drop height?

 

you dont use springs with the coilovers, they replace them

 

doh...I meant the coilovers with the stock shocks, which im guessing will ruin them pretty quickly?

 

Yup pretty much, if you get coil overs thats pretty much all you need, coiler overs replace teh shocks and struts. go 18's for summer, replace the tires on the 16's for winter and you will be all set. plus with coil overs you can adjsut ride hieght for summer and winter.