For that, if I understand you correctly, you'd need a decent wide band lambda probe and controller & gauge - basically what tuners use when mapping/setting up a car. Bear in mind these aren't cheap, and don't have a huge life expentency when compared to the narrow band lambda probe used in todays cars.

The little dash displays that work off the narrow band lambdas aren't worth a toss - you're engine would be dead before that helped (in my opinion)

Stu sells IAW monitor software (for diagnostics) that runs on a PC

http://www.motorsport-developments.c...iawmonitor.htm

Or you can fit a SECS monitor that shows various sensor readings and error codes:

http://www.randbmotorsport.co.uk/sho...?ProductID=294

Owning a Cossie can lead to a certain amount of paranoia, but that needn't be the case if it's kept in good order, and looked after by a pro.