Sorry to bump such thread. Some years ago I got an Roadstem Ul3 for very cheap (like 25eur), it came with some rusty steel bolts (they didn't seem original at all).
So I found this thread and bought some titanium bolts from ebay. My stem never held correctly the handlebars (first an ITM Millenium Carbon Road bar, and then an el cheapo aluminium road bar).
The bolts were tighnen correctly and even carbon paste was used.
Some days ago I realized that Extralite stems don't use regular bolts, the zone where the bolt head touch e rounded, no flat, and so are the bolts.
Here you can see it perfectly:
Here is a normal bolt:
Using regular bolts result in the head bolt not touching every part of the clamp or stem as you can see in mine:
This second one was made because a friend of mine used it and overtight it.
So, rule number one, get original Extralite Bolts.
Or use it as a paperweight (bolts cost 45eur, it is almost cheaper to buy another used stem, with original bolts).
Hope it helps in the future.