BIG ADD

6 months ago I became a family man and had to do away with my superbike and truck so now I have a 99 nissan gxe limited edition .
I have looked and looked and there is not a whole lot of aftermarket stuff out there.
I recently took the fron grill plate off and replaced it with a mesh grill looks a lot better but I need some advice on lowering .
first what are coilovers? are they hard to install
are they any different than a suspension kit or lowering springs ?
I am on budget but I want something that isnt going to jack my tires up and have a bumpy ride what is my best bet on lowering my car ?

thanks .