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I'm looking for knowledge on jounce bumpers in SRF. Anything would be appreciated. Specific questions on my mind....Does anyone know what the jounce bumpers on the Koni dampers look like relative to the Penske / where I can buy them? Ideally I'd love to know the force vs discplacement difference. Can we run the Penske bumper on a Koni (I assume the monotube Penske rod is a smaller diameter compared to the twin tube Koni?).

From the GCR

Shock Absorbers: Standard Koni shock, P/N 82X-2255-SPA1 with
standard oil or Penske P/N 280396. The bump rubber provided with
the shock shall be used in unmodified, stock condition. No Koni or
alternate bump stop is permitted to be used with the Penske shock.
Shortening the Penske shock bump rubber is allowed. All shock
absorbers must be sealed by Enterprises. Prior to sealing, the shock
absorbers will be rebuilt by Enterprises or its authorized rebuilder.

In another part of the GCR it says you can vertically slit the koni bumper to make it easier to adjust the shock.

The Koni bumper is available from CSRs most likely by ordering from Enterprises who only have 8 left and not likely to carry them anymore when they run out. The Penske bumper can be purchased here.
http://www.specparts.com/sus0053-penske-shock-bumper/