Unless they're dead, do NOT remove those Illuminas in favor of AGXs. The Illuminas are a better shock.
I don't know what spring rates the Illuminas came with, but the Teins are a bit weak in my opinion relative to the drop. If you're looking for springs, my recommendation would be a set of the current-design FM springs, along with a set of 46mm linear bumpstops from FatCat Motorsports: http://www.fatcatmotorsports.com/FCM...lumina.htm#M10
This combination (with Bilsteins and NB mounts) is what I am running on my car. It gives a surprisingly good ride- a bit tiresome on wavy roads (like northbound I5 just south of LA) but is actually better than stock on things like potholes, train tracks, etc. The stiffer spring and more compliant bumpstop seem to do a good job of preventing the suspension from harshly bottoming out when you hit something big.
Actually, with the shocks that I have I wish I'd have gone a bit stiffer on the spring rate, like a set of 450/350s. With the Tokicos however I think this would be too much. The FM springs at 318/233 would be a great choice for that shock.
Sway bars... Lots of opinions here. The general rule is that all else being equal, increasing the bar stiffness on one end of the car (front or rear) will cause that end to grip less
in turns. Obviously this effect is relative to the springs that are on the car, as they too will change the front/rear bias of the vehicle. In fact, I'd consider springs to be the primary setup tool, and sway bars to be more of a fine-tuning adjustment.
Initially, I installed a set of solid aftermarket bars- 7/8" front and 5/8" rear. Pretty much the "standard" combo from JR, FM, etc. This combination does not
retain the same handling characteristics as stock- the rear bar stiffened by a greater amount than the front bar, relative to the stock setup. This caused my vehicle to be far too tail-happy, and I spun it several times- the last of which involved a tree. The RB setup is somewhat better in that the front bar is 15/16, so it's not going to be as
oversteer-biased as the others.
After some experimentation I decided to stay with the 7/8" front bar, but I removed the rear bar altogether. This actually biases the car a good deal further towards understeer
than stock, but since I have a turbo and a Torsen LSD, I consider this to be desirable. I can steer the back end with the throttle if I want to, or coast through turns at neutral throttle and not have to worry about spinning.
A comparable setup would have been to install a hollow front bar and use the stock rear bar. This would retain similar bias while decreasing body roll overall. But since I'm cheap and I already had the solid front bar, that's where I stopped. I'd suggest you try this first- purchase a Racing Beat tubular front, and leave the rear stock. See how you like it. Want more oversteer? Install a RB solid rear bar. Want more understeer? Disconnect and remove one of the two end links on the rear.
I'm going to give a plug here for FatCat, since the owner, Shaikh (pronounced like Shake) is a friend of mine and had done some really great research on NA/NB suspension setup. He's of the "try something new and observe the results" school of thought, and some of his suggestions, while seemingly inconsistent with conventional "wisdom", work. Spend some time playing with his interactive suspension calculator: http://www.fatcatmotorsports.com/FCM_MSDS_v7_6.xls
then give him a call and chat for a while. Even if he doesn't get to sell you a set of re-valved Bilsteins, he'll offer you some good advice as to how to set up the car for your particular tastes. Tell him I sent you. No, I don't get kick-backs.