...Larry Sheppard (Mopar Performance/Direct Connection) says to install your H pipe about 12 inches past the collectors.
the only benefit is noise reduction for street cars.
I've always thought about it like this...if your muffler is a restriction, but you have two instead of one (Like connecting one bank of cylinders to both exhausts by an H or X pipe), wouldn't that be 1/2 as restrictive and therefore a benefit?