IMO the Z failed because the twin turbo version MSRP'd for $45k. That's steep any way you look at it. Look at Nissan's line up today and you'll see that $45k will buy you almost any car they make, including luxury Infiniti models. If they did the S14 K's at $28k (which I think is the rough Yen conversion?) they would have sold their asses off. Of course fear of failure probably prevented this. At that price point and configuration, it would have absolutely no competition as there was nothing like that in 1996. The only thing close was the MR2 turbo, which ended in 1995, but was also a true coupe and not a 2+2 like the Silvia.

This reminds me of a similar story about a car that came out in late 2001; the WRX. Subaru took a huge risk bringing the WRX over. They were ready for failure, but Subaru was sucking in the US and wanted to try it. Subaru of America had been telling the Japan office to do it for years to no avail. We all know what happened next. With no other turbo AWD cars on the road, the WRX took off. In 2002, it sold >36k units, 50% more than the 24k that they planned to export. In just that one year they sold more 2002 WRX's than all other Imprezas to date combined. Now, every car they make has a turbo option (Tribeca is an SUV and doesn't count).