Hi to every one! I m new here and i need some help about the rear shock conversion.

I purchace a kit of air shock from:

SLSCONVERSION.COMAnd i want to know if someone have buy one of those kit! It is not working on my car !!! And it look exactly the same as on is website. The problem seem to be that the shock it self is about 3 to 4 inchs to long, first:
The piston is all the way in the shock and the car sit on it. Second: If putting air in it, about 120 psi. the car is raising, well ok but the piston is still full inside, only the ballon in the shock is raising the car, so there is no absorbing effect on the car, just ride like with to basket ball ballon under the car! So i figure that they are 3-4 inchs to long ! I can not run the car at all cause its to bouncy and dangerous. I paid about 275$ for this kit, including the shipping. Somebody can help me for this problem, cause it look like i m the onlyone to have purchace a kit like this and i cant not find no more is link on E-bay ! Thank you in advance, Maxime