On my 2005 STi im running Tein Lowering springs on stock struts on all 4 sides.

when driving at low speeds there is a clunking noise in ONLY the rear, but when driving at high speeds or hitting bumps on the freeway the noise is non existent. Im not sure if im the only one having this issue or what to do about it. Since my car is covered by warranty at subaru they are replacing ALL 4 springs with stock. Is there any fix for this or do i have to stay with stock?

Any Answers would be amazing.

 

I think that's normal. Or it could be your bump stops. What's the mileage on your car? Got any pics? I wanna put springs on mine too but idk which ones to get..

 

Look up how to re-grease STi struts. They clunk as they age.
Are those Tien S-Tech's? If they are they will too low for your struts(to be honest I don't know of any strut made for the Impreza that can handle being that low for any length of time). They are well known to be perhaps the worst springs made for our cars.
Good luck.

 

Not sure of they are s-techs honestly, they were on the car when I bought it, mileage on the car is 49k

 

At 49k you probably still have some life left in them, unless those are S-Techs and have been on them for a while. Take a wheel off and look up a part number. They should be labeled. If they are and you do plan on re-greasing the struts you might want to think about dumping the springs. You will be riding on the bump stops if they are S-Techs. Some guys love them for how they look because they eliminate the wheel gap. If that is what you want then honestly you probably bought the the wrong kind of car. Subaru designed a large fender gap in these cars. The suspension also does not do well when it is lowered more than about 30-35mm.
The bottom line is its your car. If looks are more important than how the car drives(for some people looks are all that matters) then leave them on. Remember that 1.5 inches should be the maximum(perhaps a bit too much) drop for the car to perform well. 20mm is probably the sweet spot for drop, but guys **** and moan about the wheel gap.
Enjoy your car how you want it to be.
Good luck
Edit: If they are going to replace them with stock under warranty(still under warranty?) personally I would do it. I am not a fan of Tein springs in general. Drive the stock springs for a while, then when the struts die you can do the full spring strut upgrade. Oh and please don't fall into the coilover trap.

 

Yes I was planning on doing the stock suspension swap they are doing, I planned on dropping the car a slight bit but it's lowered a little more than I wanted (it was lowered when I bought it)

 

Tein sucks. At least you know that.