[W126 Coupe] performance

[jack emery]

I have given up ideas about supercharging because of the cost. I have to 
have everything done by specialists, & have likewise with nitrous because it 
is so ephemeral.
It seems that turbo charging might be within my budget for my Euro 420. Is 
this fairly straight forward for a specialist to fit & adjust/tune controls? 
What is the best unit to use & what "side effects" could I encounter?
Jack OZ