Ideas for suspension

[cyberguy]

I have a MY2010 D4D Yaris and recently after upgrading the ECU (115HP and 250 nm) I changed my rims to Japanracing Jr3 15x7 40ET with Toyo R1R (195/50/15) in order to get some more traction. The result was great, I have much better grip but I have a new problem. In fast long turns the car raises the inner back wheel (with stock rim/tire dimension I had no such problems in the same roads) and the Traction control is using the breaks to lower the speed.

I suppose that the problem appeared because R1R has really hard sides and the height is lowered to 50 from stock 60, so the tire does not absorb anything, resulting in all force stressing the front outer suspension.

What I am thinking as a solution
1)change the rear sway bar to a thinner one.
2)KYB AGX Suspension with eibach springs
3)Bilstein coilovers with custom springs

Has anyone experienced a problem similar to mine? If yes how did you solve it. Also if anyone else has something else to suggest, I would appreciate it.