If you have a BMW pre-1991 (I know several of you do) there is a group buy for some awesome, NLA (no longer available), long tube headers that our own Bullet Ride has organized over at r3vlimited and mye28. They are available for 2002, e12, e21, e24, e28, e30 (m10 and m20) and can come ceramic dip coated for a little extra $. This coats the inside and out for maximum heat retention in the exhaust gas to maximize exhaust velocity and cylinder evacuation.

Here is a link to an oppo post with a video of them in action.