With aftermarket control arms, you sometimes need to go back through and take the wheels off put the car on jackstands so that the suspension is loaded like it would be when the car is on the ground. Loosen up the arm bolts to the chassis and bounce the car a bit to work the bushings loose, then tighten the bolts with the bushings in the normal ride height position it can help keep the bushings from being bound up at ride height. Also its always a good idea to put some Anti Seize or white lithium grease on the bolt where it goes into the sleeve, and always make sure you clean the corrosion and rust off the bolts before coating them, this can help keep the bushings quiet for a longer period of time.
Aftermarket parts are always going to take a bit more care and maintenance than factory parts. This should be solvable with ease.