Well, it will make it loud.
If you want loud, take off the mufflers. (If you want really loud, run the pipes through the interior).
Just look at all the people with rice and the garbage can mufflers. Their noisy cars seem faster.
Your actual performance will not change one bit.
To get more performance out of cars, you must make radical changes. These changes are expensive. They also reduce driveability and safety, and create more ongoing costs for repairs. Modified cars are a headache. I know, because I have done several.
The best thing you can do with any car, particularly an older one, is keep it bone stock. You will get the best combination of reliability, safety, and performance that way, because that is how the engineers made it. They knew what they were doing, and given what the car is in terms of weight, balance, and design, they put in the best brakes, motor, and other parts that fit the parameters of cost, safety and performance.
A stock older car is worth more.
If you want a faster car, go buy a faster car. Any mustang made in the last 20 years will eat your car for lunch. You can buy one cheaper than the money you will eventually spend modifying what you have.
But why do that? Your 1974 Camaro is a great car. Keep it stock, enjoy it as is, and have fun.
But that is just my take.
Besides pissing-off the neighbors and looking like a dork in a loud car you could end up with a lean running engine and burn valves or blow a hole in the top of a piston. Back pressure is not a bad thing - it just changes at what RPM the torque peak - earlier is better imo.
If you straight pipe a carbureted car, you need to tune the carburetor (metering rods, hangers), or the engine will run lean and destroy itself.
It will make it louder, It may sound like you are going faster, but you wont be. More power will be minimal and you wont know it. Its also possible to burn your valves, and you will be getting tickets for being to loud. Not worth it.
I have a 1974 camaro with a 350 small block.
