I run the XXXs rear hub carriers because the Associated hub carriers are cockeyed. If you put a TC3 with 3 degrees of rear toe on a Hudy setup system you'll discover the right is toed in 3 1/2 degrees and the Left 2 1/2. Doesn't make much difference on a asphalt track if you don't let it go to your head, but it will make the car turn right on carpet. Probably what most people were claiming was torque steer. Made me crazy even though I run on asphalt, I just hate having something like that on my car. BTW both the Plastic and Graphite carriers are crooked. I checked 4 sets and then talked to some big dog racers about it and they noticed the same thing.
The rear tower and moving the shocks out on the front makes the piston move up and down more, generally people feel it makes the car more consistent. It also makes the wheel rate stiffer so you need to go to softer springs. Other than the consistancy it doesn't do anything assuming the springs are changed to get the same wheel rate. If the springs are not changed to get the same wheel rate it makes the front end stiffer, and does all the associated things. More agressive steering etc.