I own both..

I can fit about 2x as much race stuff ie tires/tools etc in the ITR than the Lude.

Headroom? I would say the ITR has substantially more. Although I haven't sat in the back of either car for quite some time because I have no backseats in either of them. The Integra can be consider a "hatchback" while the Lude is a "sport coupe"