All right then, why haven't mfgr's picked up on and started exploiting the "thrust augmenting" tail pipes? Instead of loosing anything, you GAIN thrust (something like 3-5%).

It's not like they're difficult to build or a mystery or patented (I believe the inventor posted the formula in public forum/GTBA). Heck, there's no more material involved...

Even Gary Baker made one. :-) I don't know at this point if anyone's figured how to apply the theory to bifurcated pipes yet though.

What's a good thickness stainless for pipes? 0.007"?