I ran 11 to 1 in my iron head 410 magnum stroker. 230@.050 cam and pump premium gasoline. Ran fine with a stock ECM and incredible with a tune.

I have also run 10 to 1 on a 318 magnum with a stock cam and tight quench distance and 87 octane. Stock ECM

CNG is hard to get much range in a fuel storage container, propane is much better choice.

I am not causing global warming, I am just trying to hold off a impending Ice Age!