My car has been sagging mighty bad for a long time. Some years back, I bought a set of rear springs for it.. multi leaf. How difficult of a job is this to do without a lift? Should I try it or bring it somewhere? Also, while I am at it, I am thinking of a new exhaust system. I see alot of nice dual systems out there...my car still has the original style with one sideways muffler. Any suggestions on a nice system for reasonable $. I would like to keep original manifolds, even though I know headers would add a nice sound.