Simple answer is they are two completely different types of performance products. The TST R49 is a box that plugs into engine sensors between the sensor and the ECM. It works by fooling the ECM into adding more/less timing, duration, boost, etc. based on the setting of the TST. The TST R49 remote allows for on the fly hp/torque changes beginning at 0 and up to around 180hp/440tq.
The Smarty is a downloader. It works by loading new fueling and ECM program into the ECM. It does have a number of different program/power levels that can be loaded, but it is not adjustable on the fly.
The TST is a "timing/duration" box and can be "stacked" (used at the same time) with the smarty or other downloaders or pressure only boxes.
I run a stack with both and an EZ pressure only box. For ease of use on a relatively stock truck the Smarty is probably the right choice. The only draw back for the Smarty is that you have no gauges and should install at least EGT gauge at a minimum. The TST R49 does have an EGT and boost gauge included.
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