pardon me for being a bit thick...but if the compression is even across the cylinders where would the leak be coming from...and does it matter that there is little leaking? Is this an indicator worth anything in this discussion? Sorry...learning the expensive way, I guess.

Best thing you can do is spend the money and get an independent PPI done.

As far as the compression check I did mine after a rebuild and got numbers from 195-203. I have a non stock cam. Rarely are you going to get exactly the same number on all six cylinders. Being consistent is important but low compression is not a good thing. Most Carrera's are generally around 160-170 in compression numbers.

The leak down tells you wether you have valves sealing well or if the rings are not doing their job. Listening to where the air is coming from tells you were the possible issue is at, rings or valves. I have done a leak down on mine twice since the rebuild and has been consistent at 3 to 5%. 30% would a deal breaker for me. A top end would be in the $4000+ range and that is if everything is in good shape when it comes apart.

Carrera's also have head studs that break as well. Mine had 2 broken at 88,000 miles. Only a problem on the exhaust side studs, they are made of dilivar. The intake side studs are steel. A PPI will tell you if there are any issues with these things. Again JMHO to get an independent PPI and you will not have any doubts about the shape of the engine.