Well, Craig(?), you are throwing out quite a challenge here. This issue is almost a subject for a dissertation in internal combustion engineering.
In general, a crossover pipe in an exhaust is part of the overall engine tuning. One of the most difficult parts of IC engine tuning is providing performance over a range of rpms. Most engine designers pick a range where they expect the vehicle is mostly operated in and tune it for max performance in that range. Exhaust back pressure and resonance is a very important part in achieving an optimized exchange of burned and fresh load in the cylinders. Basically, you are trying to use the gas flow in the exhaust to "suck out" burned gas from a cylinder as soon as the exhaust opens and also use the back pressure to prevent too much fresh load escaping through the still open exhaust valve during the overlap period. So the goal is to have the cylinders in a multi-cylinder engine interact with each other through the exhaust. Of course, this can only be achieved in connection with the other tuning parameters, e.g. ignition and valve timing. The more cylinders you have going into a common exhaust, the more room you have to play. And there are always trade-offs. Gains in one rpm range may be made on the expense of losses in another range. You want to make the gains in the "useable" range. Numbers on paper don't always reflect that. Best example are the Harley "straight pipes'. Over all the noise that these things make, the riders completely miss the fact that their bike is now slower than it used to be because it has less low end torque - something you need to accelerate fast from 0 to 70. What good do 90 ft-lbs at 6000 rpm in a HD do you? Also, huge horesepower numbers are good to sustain high vehicle speeds, but do not indicate performance available in the street riding mode. This space does not allow to go too deep into this, but I would throw out the following statements: The crossover pipe on the late model (81 and 82) CBXes was added to increase low end torque for improved roll-on performance (low end torque). This does not necessarily mean, you will get more low end torque on your 79 by putting a BSM w/crossover on. You most certainly will alter the state the bike is tuned for , i.e.: changing the point and maybe value of your max HP and the shape of your torque curve. Then again, the whole thing may not be of any consequences to the performance of the bike the way you ride it. One thing though, your carbs should always be well adjusted to the exhaust your are using. You want to avoid both wet plugs AND holes in the pistons.
To be understood is the exception
To be misunderstood is the rule.