I already asked a similar question awhile back.. my thread was only 2 pages down:
SPC vs SPL Rear Camber Arms (Reliability vs Durability)
However since we're here, SPL is a higher quality but you will have to dig into your wallet more. Also, are you tracking your car? If you are then I highly suggest you go for SPL.
I ended up choosing SPC (mine came in a box with Eibach on it). After 2 weeks its been fine lol.. knock on wood. I'm only using my car as a DD and havent even pushed her over 100mph yet.
Since you're on KWv3 on a 1.5" drop I think you'll need front arms as well. Only SPC has these not SPL.