Stefano..
Anti roll Bar.
As you live in Switzerland a off the shelf alternative to Nigel Winchester's Anti Roll Bar, would be the standard TR6 Anti roll bar kit, used by many AC Ace owners with great success.
This subject was on the Forum a few years back, I believe part numbers were confirmed at the time.
If not I can Confirm, just need to go through receipts.
Either system will tighten up the front end of your Ace. However if you are planning more track use than road use you might want to experiment with different diameter roll bars, plus set it up for easy adjustment to suit wet or dry track conditions.
Cheers
Keith ..[
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