Spoke with Andrew at AR Design and they have not come up with downpipes for the d yet. I think part of their trouble is that they cannot find a volunteer in Colorado. I am trying to see if they would consider coordinating something with an east coast shop/fabricator in which case I would volunteer my car.
Anyway, Andrew did share with me they are now selling the ESS Direct Flash tune for the 335d. It's a handheld programmer, so not only does actually reflash the ECU the tune is reversable. This is an interesting development since the last time I conversed with ESS their tune was not available for US spec diesels. 55hp gains. I have an e-mail into ESS to confirm that this tune is in fact available for US cars.
If this is true, this would amount to a nice advancement in the area of true "tuning" options for the d.
Here's the tune...