The problem is that you have to be carefull when driving with lowered shocks.
And also you should have got more stiffer springs and shocks to avoid touching the body with your tires. With front wheel cars you have to make them oversteer a little bit more so they handle better. But if you get too stiff suspension you'll get too much oversteer which will be bad.
If on your current setup the tire touches the body while changing lanes at like 140 km/h etc , then surely you need to stiffen it up a bit, just a bit , not too much and not too little.
And if you feel like you have started loosing grip then i think it means that you need to upgrade the tires and get wider or sfter ones to improve grip.
And you also mentioned that tire was touching while on bumpy roads etc. At those areas you just have to be slower than normal , or otherwise you will screw up your suspension very quickly. These type of suspensions are for performance not for bumpy roads.