Your issue is not being heard, it's being seen.
The #1 excuse for most car vs motorcycle accidents is "I didn't see the motorcycle".
The most effective way for other vehicles to notice you is to make yourself more visible. At speed and distance, all what most drivers see the majority of the time is one small headlight, a very tiny tail light and a figure camouflaged in black until you are up close and personal.
A hiz viz vest or gear, high beams and good defensive driving positions is what will keep you safer. Placing yourself outside of a driver's blind spot will help a cautious driver to notice you before cutting you off. Also A loud blast from an car/air horn on a motorcycle gets some attention too
. Which BTW is a good inexpensive mod to do for about $20. Riding with your high beams on can make you more noticeable from a greater distance and in traffic as well.
Example; Here is what the Phillips Motovision bulbs
look like on high beam during the day shining into a camera lens.
Just about every week I see a motorcycle accident on the news and the majority of those accidents involve Harleys with loud ass "life saving pipes". The majority of those riders sit low, move slow, and blend in with everything around them.
Don't get me wrong, it's your bike, but if you feel like a louder exhaust can actually make so called "retarded" drivers hear you and respond immediately and correctly to a loud noise they don't recognize or that they can't see the source of, then by all means you are entitled to install a loud exhaust. Just don't be disappointed when nothing really changes. After all your concern is safety right?
There are plenty more things you can do to enhance your safety for the same or less amount of money that you would spend on the MGP exhaust. For example a good set of tires can make a world of difference in stability, handling and traction, Shimming the needles can change the exhaust and intake note to be a little deeper, sintered brake pads stop better, adjustable levers make hand positions more comfortable and easier to control the brake and clutch, paying closer attention, anticipating and reacting quicker makes one a safer rider.
Good luck, be safe and ride smart.