I believe that no matter which you choose, they all do about the same thing, add fuel, some also take care of the timing. Seems that each box has it's own unique property. The Ez adds some fuel and timing, the Power edge adds major fuel, the Pro-comp adds major fuel and timing (same as having an Ez and a Power edge piggybacked, but in one box and has the ability to custom tune your fueling to suit your needs). I have no experience with the VA box, but I believe it is similar to the Edge, without a boost module, the TST boxes can be purchased to either be set at one level or programable with a 9 level remote. They are also major fueling boxes and also do timing and boost, DD's box is similar to the Edge EZ, only the fueling settings are set up in a different manner to to accomadate thier injectors.
It's been said here before, but it really is the flavor of the month in regards to these boxes. Seems to me that Edge Products is leading the pack with R+D, though the same could be said for Blue Chip. Personally, I like the TST adj. remote box and have it piggybacked to the Edge Ez. I'm sure that I would be just as happy with either the new Edge Pro-Comp. or the new Blue Chip box.
Since I have the ETH, which does not respond as well to 'piggybacking' as the ETC's do, I am trying to build more HP with larger injectors and I believe I've done it with the new BD step 5's. Only a dyno run will tell for sure, but I have yet to even turn on the TST box since their install. They make my truck feel like it did when the TST box was set on level 6 (it's a comp. box) with the step 3 injectors.
We all have our favorites, upgrade your truck in the proper order,pick your poison and have fun

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Scott W.