Thanks to forum memebers support youve saved me more than 2 grand.....collected car from Lex Wolverhampton on Tuesday...conflicting ppwk from them (one said low compression cylinder 4, the other cylinder 8) also now stated my MAF sensor faulty, and coolant found in the faulty cylinder (not sure which one, 4 or 8) and rough idle (which i didnt notice) prob due to bent piston.
When i collected car, noticed no engine mgmt light on and car ran fine. (it never felt like it had run dodgy in the first place to me though)
Took to specialist......called me today stating engine near perfect - no loss of compression anywhere - no missfire or rough idle ....they also confirmed Ians an Macs comments ref max compression at that ratio...cheers guys...
Anyway....result !!! My car back and still 2 grand better off than if i had trusted the dealer!