Solowerks are very similiar to FK Streetlines they are bare metal which sucks for PA winter, but will get you low and ride decent. $500
Racelands are just a super cheap way to lower your car. Might not ride too bad if they are not spun all the way down. Not great Quality. $200
Differences include Materials, Quality Control, Adjustability, Warranty, Ride Quality, Handling, Customer Service.........YGWYPF.