Laffer Curve Effects?

The Congressional Research Service did another study of Laffer Curve effects and found nothing.  Kevin Drum:

Do lower tax rates produce higher economic growth? Everyone agrees that taxes produce deadweight losses, but those losses are fairly small and are often offset by the benefits that a strong central government provides to an economy. When you net everything out, low tax rates don't seem to have a big effect.
But this is in the news yet again, since Mitt Romney promises that his tax plan will be revenue neutral because his tax cuts will supercharge the economy and thus produce extra revenue to make up for his tax reductions. So the Congressional Research Service took another look at this question for the period 1945-2010, and... Low tax rates [on the rich] appear to be associated with:

• Higher investment
• Lower savings
• But no change in growth rates

None of these three results were statistically significant, but a fourth result was: lower top marginal tax rates mostly benefit the rich, leading to much higher income inequality. The study found similar results for capital gains tax rates...
One caveat: Generally speaking, marginal tax rates were high from 1945-1980 and low from 1980-2010. So the CRS results might just be an artifact of the fact that growth was higher during the postwar period and lower during the post-Bretton Woods era. In other words, it might have nothing to do with tax rates. But of course, that's the point...

The fact that the low-taxes-on-the-rich era has had lower savings and higher investment means that the US has been borrowing more from abroad and a reduction in net exports.