I am looking to add a new throttle body and a CAI. Also I am going to buy flowmaster original 40 muffler. How much faster will this make my car. Also what about a tuner? Is there anything else I should know or do to my car to make it faster and gain HP?
You could do every single modification possible for the pre-2011 V6's and it will only give you maybe +15hp. You're really throwing your money away when trying to mod the V6's. I've been there and done it.
A throttle body will not only NOT make your car any faster, it will make it slower. A CAI will add maybe 1-2 HP, if that. The muffler will do absolutely nothing, same with a tuner. The only way to make a pre-'11 any faster is with forced induction (supercharger or turbo).
I once was in the same boat you're in. I had a V6 and had money to spend to make it faster. After a lot of research and trial-and-error, I realized that modding the V6's is just a waste of money. I learned the hard way and threw money down the drain.
Is it a stick shift ? Don't even bother with an auto....
A throttle body will do nothing for you unless you have a forced induction setup.
The 3.8L v6 basically sux. I had a 2000 v6 for a number of years and did a lot to it. They aren't the worst cars out there but trying to make them fast is a pain in the ass. My advice would be to focus on upgrading the suspension. Spend money on parts you can easily replace and keep the originals. When you upgrade to a GT/Mach 1 you can take the parts with you (Cobras have different rear suspension, not interchangable).
If you really want to spend some money on the v6, I've got a set of JBA headers and a MAC cold air intake both of which have been jet-hot coated silver and a 50 state legal.
Stay away from flow master mufflers on motors that need exhaust flow, they will do nothing more then make your car louder. Borla makes an exhaust kit that Ys out into dual exhaust. It really doesn't work well without the GT bumper and it really sux to install it as it is a slip on/clamp type kit. The kit does sound really good however.
Supercharge it or don't bother. Personally I'd just save that cash, then sell the V6 and buy a GT with the supercharger funds and cash from the car. I guess if you want to be different, you could get the V6 on par with a stock GT or a bit faster, but it'd be cheaper in the long run to just save up and get a GT.
I still say upgrade the suspension and you will enjoy the car a lot more. You can also swap a new 5.0 motor in or a stock 4.6/5.4 motor in fairly easily. I was going to do that with mine until that dumbass smacked my car up.