Is it possible to run dual carbs without other engine work? Certainly.
Will you get any benefit from the dual carbs (other than looks) without other engine work? Probably not, and you may actually lose performance.
If you do your homework, and do everything (especially the selection of carbs) perfectly; you should see maybe a 5~8 percent gain in horsepower (WOT only), and fuel economy.
If you just "throw on what you have" with no regard to applicability to the engine, you can easily lose up to 20 percent in power, and more in fuel economy.
Now, if at the same time you switch to selected dual carbs; you also do head work, change to a more aggressive camshaft, and a better exhaust you will see some major increase in power without a major loss in fuel economy.
Jon.
