You already have different slip on mufflers , that is most of the sound difference. Adding a A/C and Tuner will improve performance and probably help with decreasing heat a little but unless you also change out the headpipe to get rid of the "catalytic converter" there wont be much more change to the sound.

 

Not true! The 'air filter' is actually a muffler and reduces noise at the top of the engine. The first thing I did to my old Glide (bought it new and bone stock) was to change the filter for an SE and I was amazed how much noisier it was.

As for 'stage 1' that is an expression which has lost it's way over the years. Compulsory emmissions and noise regulations alter both the sound and performance of our bikes, compared with what they could be if liberated. The ignition timing, cam timing, fuelling, plus exhaust and intake mufflers are all things we can change, to complete the package. Changing only one or two is not likely to have much benefit, more likely to cause problems.

 

IMHO, a Stage I upgrade is typically done to boost performance. That said, a common by-product of the Stage 1 upgrade is better sound. Why? Because the customer typically adds performance headers and/or slip-on mufflers at the same time.