the ZR-1 is non-turbo its just worked to the sh1thouse. i think they released the normal corvete then lingenfelter workshops baught a heap and did them all up with head work, mild bodykit, exhaust etc... and they can REAL powerful, and then he sold them run-in yet brand new. They are 60g's but well worth the price if u are serious about your C4. my dad won't shut up about them actually.
Has the vette u are looking at got the see-through roof? definately a must have item...