Was the 275 you were running before the 555R or just a street tire? I couldn't really tell from your post.
What kind of blower do you have? If you have a centrifigual blower, then it can be a lot more difficult to get into boost in the 60', requiring a looser converter and/or steeper gears.
With the 555R, you shouldn't have much of a traction problem. You do need to get them nice and hot though. When you do the burn out, burn them HARD and make a big'ol smoke show. Just when you think they are hot, go a little longer. This tire likes to be hot. I run 18-20psi in my nittos, but didn't notice much gain going lower. Going higher, I tend to spin a little more. When you launch on the nitto, you have to launch a little more carefully. It might help to pre-load the drivetrain, by holding the engine against the brakes, maybe to 2000rpm. Then, roll onto the gas on the green light, to get a smooth start. Shocking the driveline will cause tire spin, especially on the 555R.
I suggest practicing your launch and making that work well before playing with the
suspension... but to answer some of your
suspension questions: CC plates are simply for allowing better alignment of your car, especially if it is lowered. Thus, it isn't useful to improve your drag times. Removing the front sway bar helps the front end lift up, and improve weight transfer. You can just disconnect it at the track for most of the benefit, but taking 35lbs off the nose helps a lot too.
. Set your front shocks to the softest setting, and your rear shocks to the firmest setting. More firm in the rear will help prevent the back from bottoming out, and softer in the front helps the front end rise.
I think the main thing, will be to work on your launch technique. You can not shock load the 555R. Make a gentle smooth launch, and if you can break them loose by slowly rolling on the gas, I would be shocked. With my 245 width nittos, I've gone quite a few hp limited, high 1.7 60' times.