Could my flowpath be messed up???

I went to the muffler shop yesterday to see if I could run my exhaust out to the side but he recommended not to do it. He said that the bend in the pipe would be too drastic and would stop too much air, is this true?? Ok so then he taps the driver side muffler and it sound likes somethings loose. He keeps tapping it and then it stopped. Could this muffler be bad? Another reason why I ask is because when I'm driving normal, the exhaust sounds flabby, kind of like an old, weak chevy truck. Not completely flabby, cause when I rev it, it sounds mean as hell, just at cruising speeds. Having them as cut offs have anything to do with it?
 
I cant comment on the problems with the mufflers but you can cut bend the exhaust out the side. My buddie has it on his 96 gt. Looks good, although the pipes do an s type curve to get the angle right going out the side. I dont think it will make any significant restriction to slow the car down.