I have always thought that crossover pipes were intalled for equalization. I have a lot of muscle Car friends with Hi-performance motors and only half of them have cross over pipes. The "X" is definately better than the "H" as is scavenges better. I understand from talking to them that these crossover pipes only benefit these big motors at full throttle and really don't increase HP but rather make the exhaust system quieter. The Muscle car guys would love to run 3" or 4" straight pipes but the local police don't like it. The cross overs do reduce the sound by at least 30% so that's the main reason for having them on the street. You don't see true race cars with cross overs so that should tell you something. The less restriction the more power you get.
RapRap
1940 ChoppedChevyCoupe
