as a Backdraft owner, I'd say the overall fit & finish of a Superformance is slightly better- as is the paint. BUT... I LOVED the fact that the suspension was BMW-sourced... and the 2 inch stretch makes for less "squirrelly" handling at the limit- and it IS a very comfortable car, as Cobras go.
One thing that no one has mentioned yet is that Backdraft has one of the most nicely-finished engine compartments around. All the polished stainless really sets off a nice engine.
Exhibit A