I have 1993 Del Sol Si and it was lowered with Tein springs (1.5 ~ 1.8 inches) on stock. It has been 2 years since I lowered it..... alignment is perfect...
I started hearing a high pitch noise coming from the front wheels a few weeks ago, and now I can hear it continuously (not loud) when the car is moving. The sound reminds me of the brake pads squeaking or rusted belt turning, but they are not the source of the sound. I don't hear any other noises coming from there and I don't feel any thumping or grinding sensation on my steering when turning or stopping.
What could this be? Where is this noise coming from?

 

could be a dragging brake caliper or wheel bearings failing. does it go away as you increase speed?

 

I don't know if goes away or the road noise is simply louder when driving at high speed, but yes, I don't hear it when driving on highway or going over 50mph..

 

I would agree with dpetro1. I'd grease the calipers pins and see if that fixes it. Otherwise I'd look to the wheel bearings.