most coilovers are noisy and tend to do this. im running hks hipermax as well and have this problem. another person i know has tein flex and same thing happens, same as trd sus kit.
its due to a number of things, dominantly, the coilovers stiffen up the suspension, but your body isnt stiffer, thus it takes the grunt of turns/bumps as your body flexes. swaybars help but itll still be there. if you have bigger rims/smaller profile tyres the noise is louder too