I did a Google search and found this:
Eleanor’s younger sister “The Slicer” is one beautiful and tough little lady. She was the star Vehicle of “Gone in 60 seconds:2” (1989) along side H.B. Toby Halicki. Every precaution was taken to safeguard Toby’s life before he put “The Slicer” through her paces.
A very thick Roll Cage like what NASCAR uses, was built under her shapely figure and it allows her to show off that she can flip and spin any car that gets in her way. Her Fast and Furious engine gives her all the horsepower she needs to play with the big boys on the block. Her skin is bullet and car proof. She is always ready to rumble!
http://www.gonein60seconds.com/slicer.htm
Can't find any info on who specifically built it (although, if I had to guess, I'd say it was built specifically for the film) or any performance specs