Inexpensive RPM control

Just came across something interesting in Gene Berg's catalog; an inexpensive re limiter. It's a rev control rotor that works with Bosch 009 distributors. You can purchase rev control rotors for 5,400 to7,300 RPM shut off. These are stock in Porsches from the factory (says the catalog). Price is in the $30-$40 range (my price catalog is from 2000 so the prices may have gone up. Anyone heard about these rotors?
Catalog number: GB 622D to GBN622H

I know they were stock in type four van engines

Yeah, those are Bosch limiting rotors for Porsches; I have one to install in my 009 that should cut out at about 6,500 RPM. CB Performance and John Connolly at aircooled.net sell them also.

These are a very good idea for any performance engine as floating the valves due to an over-rev can be quite expensive. And, performance valve springs tend to lose some of their strength over time, especially if you rev it up high often; so springs that would safely allow 7,500 RPM when new might float the valves at 7,000 RPM a year later.

I like this rev. limiting idea,it's very low teck. And if your car,(Heaven forbid) were stolen, it could very well save your engine.

My new 2165 has an MSD box with a removeable chip that limits RPMs to 6500. I have a second chip that limits the engine to 3000 RPM... even better for a little added security in case of "unauthorized driving".