i lowered my solara like 4 yrs ago.
i think TRD uses Eibach lowering springs. they're exactly the same but much cheaper.
also, eibach springs do not "over-lower" your car, like H&R. overall, my ride did not change much after lowering (except going through speed bumps

). i also kept my mud guards on, and i don't think they're damaged after the car's lowered.
so, it really depends on "how much" you want the car lowered. personally, i do not like cars to be over-lowered (like when the body is lower than the tires).