I just happen to install these coilovers on my brothers 240sx(91) this weekend and happen to use the same coilovers....The front was a bit of a hassle because of that hex shaped looking cap on it. The manual says u need a special tool to remove it, but I just filed down the edges and the sleave fit right over it. The back was pretty self explanitory. Mine had no instructions, so I guessed and used the short set of springs for the front(ive done like 20 coilover conversions, and the short springs allways seem to go up front). It dropped it pretty damn low with them set all the way up. There's about a 1" gap in the front with 205/40/17 rims/tires. I may grind off some of the stock perch so Ill be able to spin the new perch down the sleave. As of now, Ill only be able to drop it about 3/4" more, but i may just leave it. The back end is all the way up on the sleave and it leaves about 1/2" but it looks pretty damn good. Its a little bouncy, but for 120 coilovers, I can't complain, just some shortend struts all the way around should really help the handling, but that wont be for a while....
Do you think you could have put the Rear springs on the front, because the rear springs are almost twice the length of the front springs uncompressed.
Let me know 'cause im kind of curious