For anyone looking for a downpipe for a 1JZ with stock twins in an S13, be aware that the driftmotion one will hang about 2.5" below the 'frame rail'. I tried to find info on the fitment before buying but saw nothing. I'll get a picture of it next time I have a chance.
I think I'm going to get mine cut and welded to tuck up a bit more, right now it's touching the ground.
Edit:
Bad Picture, but you get the idea. For reference, it's on the S13 below.