exhaust manifold nut opinion

[John Larson]

You asked:  "Does anyone have an opinion on whether to got with the 
cheaper copper exhaust manifold nuts or the steel self-locking ones?"

The "copper" nuts to which you refer are copper plated steel.  They seem to work fine on BMWs, whhere they're OE (the ones with a flange), but not so well on Audis.  I use only the Audi OE nuts, thick washers, and studs (the ones with the little pointed bump on the end).  They're the only ones I have found to stay tight.  I'd much rather charge my customers a premium at the beginning and not have to deal with a labor intensive comeback, more parts money, and the hassles that come with it.  John