This is the test results of the captured scanner data.

As seen it made no different in the slower cruise part throttle run or the run with more WOT/higher speeds that a stock tune from GM is not adjusted for E10 ethanol and would cause engine to run 10% too lean
( worse with E15 coming out soon) and when PCM is tuned for E10 where the LTFT stay around a perfect zero that when normal gas with no ethanol is used then LTFTs will be about 10% too rich.

This shows the ethanol and the more percentage is used that your engine will run way too lean, have more engine knock, less timing, less fuel mileage and less performance

If finding straight gas and your PCM was tuned for E10 then engine will be about -10% too rich and will need retuning for either cases.

As to our custom NFW exhaust design ( review other thread about design and testing) with weather at 70 degrees at idle with windows up the exhaust sound measured between 78-84 Dba and car in motion measured between 84-90 Dba