IMO the most important thing on a street driven car is to make sure the exhaust exits out the back and not UNDER the car. This will eliminate the resonance (rumble) and will make a big improvement in the sound.

My 32 roadster has a 350/350 with a 2 1/2" X-Pipe system and Magnaflows with tail pipes exiting the rear. Sound is much better than when it exited under the rear axle.

I made mine by just using two 90 degree bends and siamesed in the middle.

If you plan on ever "taking it apart" adding some V-Band clamps is a nice addition.