If exhaust was the only mod your considering, then I would agree with you. Without tunning and other supporting mods, exhaust us just noise. HP gains are minimal at best with a stock engine.

Its best to set a power goal and decide how your going to reach it (forced induction or naturally aspirated). Then plan a setup - find out which parts work well together before you start buying things.

As far as CTR cams go, you can install them with factory valvetrain components, but you probably won't happy with the results. In order to take full advantage of them, you need:
The basic intake, header, and exhaust
Something to tune with - a socketed OBD1 ECU and Conversion Harness
Portflow inner valve springs, or some other upgraded valvetrain
And I would recomend a single stage Intake Manifold - Skunk 2 or Blox

So, spending 600$ on that exhaust might sound like a waste now but if you plan on getting cams or anything else later, it will pay off in the end.