We just fired up the updated engine in the Sunfire. The exhaust note is much quieter with the Methanol compared to Gasoline. It is the same engine combination except for an intake manifold change. Is this a common happening?

I have noticed the same. Especially at idle and low speeds. More than once, I have commented on the methanol idle sound, [which is slower and quieter than gas]

One thought: because methanol carries oxygen, which enhances the burn, the engine will have the same low-speed RPM with less throttle opening. At wide-open throttle, in the sweet part of the power band, I think it is louder.