24mm is the biggest rear bar you can get.
Also, just because there is a emblem that states Performance Package on the dash, doesn't mean it has the WS6 package.
Depending on the year of the car, grabbing a wonderbar is a great item too.
You can only find these on the IROC-Zs.
Not all cars got the RPO sticker on the cars.
This came out around 1985.
Hope this helps,
George
