honestly, they are not worth the rebuild. Tein uses garbage valving. they are basically a throw-away coilover. once they are worn out, toss 'em. BTW, if you dont like spending $$ on rebuilds, you should never have bough coilovers to begin with. if you think they last as long as a fixed perch shock, you are fooling yourself.
That being said, you can have real good parts put in to them, you just have to find a custom shock builder to do it who feels comfortable using the tein shock body. you will pay a lot for this though, but they will still have to be rebuilt periodically.
4-Time NNJR ESP Season Champion -15 ESP
3rd Place in 09' Pax Championship/Driver of the Year
2012 Northeast Divisional Champion in ESP