It truly depends on the roads and personal ride feel to you. You could go with a Pss9 and adjust it for a few hours till you get the right height and wheel feel. Just remember the lower your car the stiffer you want your ride. since you have 18" if you don't want a stiffer ride keep it as is. If you hit a pothole at night or something else your shock can't travel very far b4 bottoming out. Which may ruin your day,shcok and rim. If you have a set budget think about a adjustable suspention. Also remember the first time you go down a new road may be the last time, potholes, dips, debrisall could f- your sweet ride up.
"Drive like you live" CFBA:rocks:
335i will be the new turner car for this decade!
If it's a bimmer, it's badass.
It's more fun to drive a slow car fast, than a fast car slow; F- That just go to driving school and you can do both.