Coilovers are too hard core for normal road use,due to our shite quality road surface.

I'd go for Eibach springs,they make the handling a bit better,improves the looks and keeps the ride quality good.

I've had Eibach on almost all my cars and can't fault them,got Eibach/Sachs set up on my RS and its spot on.

Oh and try Ford for the Eibach springs,thats where i got all mine from i found them to be cheaper than anywhere else.

PS. How dodgy is your sis's reg number? lol