I got the GT takeoffs and was very pleased. Depending on your preferences, you might do as I did: try a stiffer rear bar than the GT one. I did an ADDCO bar for a while, very good and less understeer.
Finally, changed to a one-inch (26mm) rear sway bar from H&R. This is a marvelous piece of work, sturdy aluminum body links, special bushings, very nice finish on the bar itself, and It Works: car balance is neutral, and it will understeer or oversteer at your bidding and in the degree you request. Plenty of confident car control, a real joy to drive, on and off the autocross track.
Best mod to suspension was Steeda Sport springs that made it look better and handle better. Lowered the front ~ 1 inch, rear ~1.2 inches. That was just before the H&R bar. Since then, I added Tokico D-Spec struts and shocks, which work good on the streets and highways; haven't done an autocross since them.
No one setup will please everyone. Sooner or later it's between you and the seat of your pants.
Today was autocross day at Qualcomm Stadium. Two base-line runs showed all the same performance characteristics set out in the "Finally ... " paragraph, above, were still present: neutral steer that will go to over- or under-steer at your command, flat cornering, good sensations of car control.
Then I followed the Tokico manual's suggestion to reduce oversteer: dialed the rear shocks out to "full soft" (seven and a half turns from "full hard"). Result: understeer in places it was neutral previously. Could still provoke oversteer, but not as easily.
Next, dialed the rear shocks to three turns out from "full hard", which is two turns firmer than "normal". According to Tokico, this should result in more oversteer, and it did: same kind of change as the step before, but in the opposite direction. Oversteer in previously neutral conditions, understeer available, but not without some effort.
So, I reckon it is sorted for the present tires, and I'm confident there are adjustments to compensate for any changes I might try in the next few years.