The Bischoffs were introduced with the 94 model year and all 94/95 993s have this style. They are characterized by an oval outlet with three individual tubes leading into the collector. These are called “Oval” and we make the Oval Crab. These are the ONLY kind of 993 exchangers we can mate the “RS Crab” to because the “Round” exchangers will not fit under the early bumper.
In 1996 Porsche began using a 2nd vendor, Gillet, which have a different design and a round outlet. These have a block collector into which the three header tubes dump and a perfect equilateral triangle hold pattern on the output flange. These are the “Round” exchangers. Note that 96-98 993s may have either. Please refer to then as Round or Oval when you order, as we often get confused!