I seen a camaro where the mufflers cam right unter the center of the car, not far from the headers! is there better performance compared to the longer 3" all the way to mufflers in the rear end of the car?

short vs long?

 

What you thought were mufflers were dual catalytic converters going into a single 3' pipe to a muffler with dual outlets. it was a option on later model 350 TPI cars.

 

they could've been glasspacks if they were right after the headers