I tried the Sonics, they squeaked like crazy which is probably why they don't offer them any more. I forget the diameter of the RE springs but no one made a perfect match, so I got a slightly smaller diameter from Sonic. Sometimes it works, sometimes not. It didn't for me.
You can always take out the springs, do the math, figure out how many coils to cut off to get the spring rate you want and do it. You'll need to heat and collapse the last coil so it sits nicely but it's not too hard.
Honestly, just replace the stock oil with the proper amount of a good 10W fork oil. You'll be amazed at the difference.
Scott