Shift kit improver or transpak

Whats the difference and how hard are they to install......

im rebuilding my transmission with a friend we both have build tranny before but we have never installed a shiftkit...............

very simple. it has instructions and apparently is very easy to do, or so sez my friend that did one. the shift improver just makes firmer shifts and the transpak adds to that by allowing you to force the transmission into a lower gear whenever you want, overriding the factory settings, so if youre going 60 with a car that has a th400 three speed auto, you can make it shift into first if you want. you can also force it to not shift up until you slap the shifter up a gear, so no more upshifting too soon. the cool thing is that if you leave the selector in drive, it will function like a normal automatic would, so you can drive it on the street as a daily driver if you want to. also, the firm shifts only are tire-chirping when you're really laying into it, and the tranny will shift smoothly when accelerating normally, or so they say. i plan on installing the transpak in my th400 this spring and i think its well-spent money