Any reason why I wouldnt want to mount my downpipe to the turbo with exhaust manifold copper nuts?
Maybe if you are allergic to copper???
Using the thick washers too?
Only reason not to,... because you are cheap/lazy.
Thay are spendy for nuts/washers and it does take some effort to aquire them

Oh ok.
I have somehow come to own a large bag of these.
I vaguely remember buying them years ago.
Today I was searching for some nuts to mount my downpipe and came across this bag.
Guess I'll use them.