Bloody hell, just read what a leak down a) involves and b)what it might reveal!!!!
Actually, think it was your reply to someone on scoobynet last year that I've just been reading.
Are them exhaust valve thingies easy to be replaced?
Ill be pissed off if its compression leakage because its totally standard, never messed with, and never given me any hassel.
I did have the lambda replaced last year because it was fucked and emissions were through the roof. That settled a lot of its hesitancy under hard acceleration, but could that have affected exhaust valves or anything to do with that sorta stuff?
My understanding of how engines work does not stretch further than about this point lol!!

And, even the coolant temp sensor is a pain in the arse to change from what I quickly read.

Grrr!!