In Reply to: Weird engine performance issue - Jim Cash help! posted by BillP on July 09, 2000 at 16:17:28:
Not that I have ever hear of - I strongly doubt it.
You mileage will go up as the engine loosens up a bit and the rings start to wear in.
You might also be changeing your style of driving and not realise it.
AND the ECU adapts to fuel grades (retards the operation if it senses any detonation).
Next time in for service have them check for any error codes - it is always possible that you had a sensor, or air leak problem that corrected itself.
If you do find out what caused the exhaust growl to increase let me know. I will do the "reverse" as I would keep the performance, but would prefer an exhaust that "muffled" all the noise.
Who needs the noise - I prefer stealth !