AST shocks are monotube design for a reason; they perform better. When will you notice this? Big bumps in turns and fast transitions on the track / autocross course are where true premium shock performance becomes evident. Ride in or drive any car with this level of shock and you’ll know instantly why people buy them, they make the difference. Other non-monotube designs on the market exist for two reasons: comfort and cheaper manfacturing expense. These are two things can do without when time on the track counts.
Consider what you get with AST products and the value for your money becomes self evident. All levels of AST shock absorber are hand built using brand new, custom housings. Even with the Performance Grade 4100 series, you are getting the internals of the 3 way shocks in a single adjustable (rebound only) coilover kit. Competitiors at or below AST prices simply do not offer the same high technology and features.