Piston ring end gaps.

[EMWynne]

Thanks Ike...that seems to be the problem, none of the manuals give the specs because they did not expect the engines to be rebuilt...but people are rebuilding...you can now buy all the parts required...so somewhere there is the correct specs.

[Homeoboxter]

I replaced the rings in my 99 Boxster because the ring gaps were pretty large at the oil rings. Here you find some reference about the gaps of used rings versus the new set I used:
Blue boxster resurrection project

[Homeoboxter]

Oh, page #6 and #7.