MSquare

The Smarty isn't sold as HP adder, it originated from the modified ECM's. These modified ECM's were called CATCHERS, Clutch and Traction Challengers. They were a big hit with the 24V crowd. They changed the performance of your truck by bringing the power/boost on much faster then the stock ECM.

Now instead of the modified ECM (and non-adjustable), there is the Smarty. It plugs into the data port connection in the cab, it has different levels of the original CATCHER program, some with timing and some without, reads codes and clears them, has a built in high idle program, downloadable upgrades and a program to adjust your speedo to aftermarket tire sizes.

IMO this is the #1 box to buy for 24V trucks.