The simplest way to make a low restriction exhaust system that won't give the neighbors cause to break out the varmint rifle every time you crank up the engine is to put a pair of mufflers for a mid-1970's Cadillac on your truck. Each one has 2 1/2" pipes in and out, and one of them is designed to flow the exhaust stream from a 500 cubic inch engine. Low restriction and quiet- - - -sounds like a win/win situation to me! Any muffler shop should be able to bend up a set of pipes to accommodate that system.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!