you will get top hats with new coilovers very straight forward swap i have recently done this the main thing is spring rate.
what are you going to do with the car? track street track and street? i have 12 front 6 rear and comfy for road use could be stiffer though if you do a search there will be plenty of info on this site and other members advice who have been through spring selection
I did the change over last month and haven't looked back. I put the BC coil overs with spring rates of 12 and 8. Only had to adjust them 2 cms higher from what they were delivered at to get clearance for some gutters. I used the forum with the photos to effect the change. She sticks like glue with little body roll now. Beaut! You won't regret it.
It's harder for sure. But you can adjust the hardness settings on the BC coilovers. I have mine set fairly hard. I must admit that sometimes she bounces out of the bumps on the road, but that's the nature of the roads up here.