How To Cure a "Rappy" Exaust?

Funny how it's mostly trucks that do this. I had a F*rd pickup with a warm 466 in it that did the very same thing. I hated the sound. The only thing that cured it was a cross-over pipe in the headpipes. In my case it was a Dr. Gas X-pipe. I was running Dynomax Super-Turbo's at the time. It made the same noise in town, but, curiously, at hi-way speeds, you could hardly hear the engine,,, till you hammered it to pass someone. It actually seemed like it increased the torque down low.