Kenne Bell doesn't make supercharger kits for a v6. Best upgrades for a v6 is a dual exhaust, like magnaflow or flowmaster. There are kits that can convert your v6 to a dual exhaust. Downgrade is that it won't sound loud enough like a v8 with a similar exhaust.
You can upgrade your gear ratio to a 4.10 or 3.73 depending on whether its automatic or manual. Best company is Moser Engineering. That would make your mustang a little faster, but would reduce the higher speeds with steeper gear ratios.
You can do other upgrades, small stuff like cold air intake, and a custom tune. With a custom tune, that might be another 30 horsepower depending on the tune. Cold air is 8-10 extra horse power. You won't have any increase really big unless you throw on a supercharger. I wouldn't recommend it unless you want to put $$$$ in your v6. A supercharger retails between $3000 and $4000. You would only get maybe an extra 70 horsepower unless you put more $$$$ in your engine first and have it with improved air flow.
Go get a Kenne Bell supercharger if you have the money. These are pricey and get a K&N air filter and Magnaflow exhaust kit and also get a catback system and your car will be not only fast but will also sound bad as$