To De-Smog or not to De-Smog...

I have to disagree, smog equipment and specs are notorious power and fuel economy robbers. The slant is just one example of the before and after of the smog regulation. The early 60's slants were quite strong stock, the late 70's slants barely got out of their own way.
When we buy parts for Ford FE engines, in example, we buy timing sets for the early engines as they aren't retarded like the smoggie ones are. Get the proper timing and you gain both fuel economy & power.
And just as a general rule we see 1 to 2mpg gain in just pulling the smog pump belt in any engine, it takes power to turn any component and that means fuel lost too.
I agree with Dan it's best to not just randomly pull stuff off. If you know what each component is doing you'll know how the engine is tuned to it and what other systems may be tied into it. But you absolutely can get rid of unnecessary problem ridden junk.