Hi guys. I have lowered my g with kw v1 coils and started to hit y-pipe for a month. I started to hear rattle from under the passenger side. Also smelt smog from the same spot.
Does anyone have same experience after the lowering? I can see mine has like 8-10cm clearance between ground to lowest point of pipe. Any advise?

 

Since you have coils your best bet may be to just raise the car just a tad. That may solve your problems. The rattle may be something loose underneath from hitting so much, maybe the shield underneath or the one in the wheel well. Hopefully its nothing more than that.

 

Found helpfull information finally here, I had my brakes done about a year ago and afterwards there was this rattle metal noise, I thought It was the heat shields, as the rattle came in over bumps. Mechanic lifted the car up, said the exhaust is normal. Started hitting the tires one by one, and that similar heat shield rattle came on. Removed the wheel and behind the rotor there is this big metallic round plate, he played with it, opening it up etc and brought the car down, the noise was gone.