i was wondering if you guys could help me compile a list of specific parts or characteristics of any automobile that create a cars distinct sound. i'm actually doing a research study on this, so it would need to be specific things, ie : transmission gear ratios and not just transmission.

so far what i've thought up (haven't spent a lot of time on this yet):
tire footprint, so diameter and width
exhaust piping diameter
header type, 4-2-1 or 4-1
# of cylinders
motor size, liters
transmission gear ratios (can be easily calculated the way my data is input)
muffler... what specifically about this though?
turbo
turbo components: waste gate, bov, etc

anything else? any response is very much appreciated, thx guys

 

Throttle body bore and taper
Intake manifold plenum volume, runner length/volume
Port configuration/volume
Valve overlap. Cam duration and timing.
Piston bore, crank stroke.
etc
etc
etc

 

Tread pattern of the tires, not just their size.

Aerodynamics - wind noise. My car makes way more noise when I have the bike on the roof!

Alternator - don't laugh, on some cars it makes a characteristic whine from those blades around the pulley.

Amplifier - like some ricer kid who thinks 50%thd sounds kewl...