hello, has anyone installed one of the fork damper kits made back in the day by Circle Industries or Fun N Fast's for a 1971 DT1 250 or RT1 360? Do they make much difference?

Looks like you lose travel if that spring goes as it is now. Or is it a spring to replace the spacer on top of the springs so maybe it's a longer damper & spring is added to stop the main original with spacer from coil binding on longer travel. Any more info on it?. Is this for the alloy slider forks not the first model steel sliders like i have on mine.
Just to explain my first sentence--PE & RM Suzuki's had a long preloading topping out spring but that's talking long travel towards 1980 so i guess not relevant.

I kinda remember these from the day, think they had different valving and the springs replaced the stock upper spacer. I used the springs but did not replace the lower piston piece. The upper spring replacement did help with some additional travel.