well i personally wouldnt do it for the reasons you mentioned above. but if your looking for a drag launch spring i think eibach makes em. if your just looking to do this because of custom hieght get a full coilover setup.

also bottoming out really cant be prevented by a new set of shocks unless they have shortened shock/sturt housings. haveing shorted housing yeild more suspension travel but usually yeilds more money.

but if i were you i wouldnt even begin to think of mixing 2 different brands of springs together. remember suspension isnt on of those things you would like to half-ass. when it comes to suspension do it right or dont do it at all!!!