My kit was delivered in 2000, so it is an early model solid lifter engine. At the time, I seem to recall Jab advertising the weight of the 3300 engine as 70kg, 'lighter than a Rotax'. This probably did not include the exhaust system, and the early engines may be lighter than the later hydraulic versions.
When I completed the build, the aircraft was professionally weighed, and the verdict at that stage was that is was nose heavy configured 2POB with no fuel (my tank is behind the seats, no wing tanks), and I was directed to instal 6kg of lead in the ventral fin. It was in this configuration that the C of A was issued.
A couple of years down the track I had a think about this additional dead weight in the tail, and decided to relocate the battery from the firewall to the back of the luggage compartment. This had the desired result, and I could dispense with the ballast.
I honestly don't know what the manufacturers specifications are for the later Jab engines, I do know that one of the advertised differences between Camit and Jab is that the CAMIT has heavier cylinders. The flywheel attachment of the Camit is also significantly different to the Jab (heavier) and I also assume that the 40 amp alternator is heavier. What I can confirm with absolute confidence is that with the old engine, the weight on the nose leg was approx 65kg. With the Camit installed, this had jumped to 83kg! This was not some sort of aberration or my eyes reading the scales wrong, it took noticeably more effort to lift the front of the aircraft to move it around.
As for the desirability (not) of adding ballast to the extremities of the aircraft, probably a good point. But this was how my aircraft was granted it's C of A in the first place, so we are back to square 1 in that regard. I am trying to think of a way to relocate the battery further rearward and maybe ditch some of the lead, but it's a bit difficult without interfering with the structure, and that is a no-no.
Anyhow, all this does not seem to have made any difference to the handling. I don't know about spins, they are prohibited!