trboam.....its function is to increase the pitch of the exhaust note by doubling the pulse in each pipe....it does very little to help the engine breath.....what it does is allow the engine's exhaust note and volume pass noise standards...as I said in an earlier post; listen to the difference between a 650 bonneville and a 750.....in the 750, the beautiful exhaust note is gone......this was entirely due to its exhaust crossover....there were many of us that got that note back by eliminating the crossover - with no loss of horsepower....and by the way, you're talking to a mechanic.....a decent one....
