stealthperf

I can't speak for the other two but I did put a tvs1900 on my 2004 6.0 2500 4x4 crew cab.... I started out with just the Maggie and their tune. It made a good difference but didn't blow my socks off as far as speed. It did, however, considerably increase the torque. The second summer I switched from a 3.4" to a 3" pulley, installed an ls9 cam/springs, 90mm throttle body and a cold air intake and worked with black bear to get a tune... Those changes made a huge difference in power. Now I went to id725 injectors (the Maggie injectors were maxed out) and 1 7/8 american racing headers (another good increase in power) Also, I was able to turn the program up a bit with higher shift points now that i have enough fuel.
In my opinion, you need a considerable horsepower increase to really make a difference on a vehicle that's heavy.. In my case about 6300 to 6500 pounds..
Installing any type of boost will definitely help but it seems to magnify the power band of the stock motor... For example, if your motor is torquey it'll make it REALLY torquey!! To really get the speed and higher rpm pull, you need to change the power characteristics of the motor by changing the cam.
I have not installed the others, but I will tell you that Magnuson has a very nice, complete kit that comes with very easy to read and thorough instructions with great customer support.