If you aren't well into Nissan modding then you won't know what it means. But for decades it has been a popular japanese conversion of the S13 180SX (Hatchback with flip headlights, reference "USDM '89-'94 240SX Hatch"). They take the 180SX and slap on the front end of the S13 Silvia (Coupe with static mounted headlights, no USDM reference). 'Sil'via + 1'80'SX = Sil80 aka Sileighty (unofficial car, never actually in production). The car itself was produced in Japan from brand new 180SX's by the Nissan dealerships they were at, where they would have the Silvia front ends swapped onto the 180SX (complete bolt-on job). It has been reported that only 500 were produced this way before Nissan corporate of Japan layed down a hammer, and the few dealerships involved ceased to do this. Afterwards, the 'mod scene' of Silvia and 180SX lovers started swapping their front ends themselves.
If you would like some pictures of such cars, just google Sileighty/Sil80. If you are in the US, then just google "S13 Silvia conversion". It's an overly common front end swap.
On a side note, too bad GT5 doesn't have any S14.5 Silvias in the game like my own personal car. (S14 Silvia with S15 Silvia front end).
