its all about exhaust velocity. an inproperly setup true dual system could be less efficient than a single pipe exhaust system and vise versa. pipe size diameter, number of bends, and exhaust components all play a factor in a good exhaust system.
Jim Hahn
1996 T-Red Contour SE Reborn 4/6/04
3.0L swap and Arizona Dyno Chip Turbo Kit
364 whp, 410 wtq @ 4,700 rpm
