Are there any way to tell if the hull is Kevlar on a Cigarette, maby a didgit in the hull number or do I have to contact the factory ?

Also how much lighter is a Kevlar hull compared to a non Kevlar hull ?

According to the 1985 Brochure I have for my 38 Flat deck the Kevlar version is 1000 lbs lighter.

I don't know about the HID numbers being different.

If you can find a part of the boat that is not gel coated, Kevlar looks very differant than glass. Glass is translucent, you can see into the layup. Kevlar is gold and opaque, it almost looks like it has not been wetted out. You cannot see into the laminate at all. This is assuming that it it is 100% kevlar, it is also possible to have a combination. As Cashbrain says a call to Bud at Cigarette is a good idea.