Download the spex for you particular model and see - don't rely on complete strangers to solve a complex issue for you that you'll have to live with for a long time.

The equation is pretty simple ( assuming the blower part even can be reversed ! ). :

Standard Cabinet is 24" deep

Downdraft unit is "x" deep and will also require clearances between unit, cooktop and cabinet.

What ever is left over will be the MAXIMUM depth you have for a drawer. Do not forget that the drawer runners usually extend past the back of the drawer box itself. SO, say you have 18" left over , you drawerbox will be even less than that.

You can go deeper but all that is going to do is push the cooktop and or vent farther away from the front edge of the countertop and that won't be very good for your back.

Some downdrafts have provisions for remotely mounted blowers - attic, basement, roof, outside wall. This would eliminate the fan box at the downdraft all together.

Thanks xedos. I wasn't planning on relying totally on strangers, was just hoping that someone had tackled this before. The blower can be reversed, I have looked at the installation instructions and I have contacted kitchenaid to ask them. My current cooktop has the closest burner 5 inches from the front so pushing it back a bit didn't seem like a big deal.

It's the back burners you need to be concerned about.

Don't lose overall perspective in your quest for a single item (deep drawer)

Good point...I will have to do a mock up and see how far back it actually is when I discover if it is even possible. The cooktop is set up much like what I have now, with the biggest burner being right in the middle. I have never given much thought to the fact that my cooktop is so deep right now.

Thanks for your input :)