I don't really think there is anything you can do to match the rear to the front. What springs are you on? How much of a rake is there? I have some df210's that I need to install and I want to run echo struts too.
If you're desperate there's always cutting or heating the springs to drop it a bit. Though I wouldn't recommend either way, it is an option if you're desperate. Heating causes the spring to anneal and from there weakens it quite a bit. Drops the car, but makes the springs brittle. I've heard stories of a place in the Valley back in the day that used to have a big pit in the floor that had a dude with a torch in it. People would drive over the pit, he would heat the springs, and then you would drive out lowered. This was back in the 60's early 70's I believe before they knew the effects of heating. Kinda cool story....anyways back from my rant. I think you're pretty much screwed unless you want to do something drastic.
Or get different springs and rub a combo setup. The 210's drop the box the most (unless you can find the fabled hks springs) and you can run the 210's in the back. The progress are like 1.8 front and rear I think, and the 210's are a solid 2.
Your best bet would probably be to but a new set, or find a set used. Swap out the backs and voila! You're done. You could also make a bit o cash to get back a bit from the new purchase by selling the combo setup. I'm sure it would sit pretty well.
That is, IF you were to take this route. I'd wait a bit more and see what others say.
I've got a set of df210's that I was about to put up for sale as a set. I'm asking $75 for all 4. Had them on my box for about 4-5 months, still have the spring wraps, and original box. Let me know if you're interested. I'm always up in the San Gabriel area, so we could do a local meet up.
XBcreep I might just be interested. The other thought I had was maybe get the adjustable rears from a coilover setup so I could dial in the rear to be right where I want it. XBcreep Ill get back to you in the next day or so.
Sounds good man! Just lemme know! Although I hope he goes for it, because I really do think it'll help to even things out. Yes, I know the echo struts are approximately 1/2" lower than the xB struts, but if you notice, all the springs that lower the car 'evenly' also make the back end sit slightly lower. Therefore, it SHOULD help even things out, not to mention that when you start weighing the back end down with audio and people....Well.....We all know why fenders get rolled.