Blimey!!!!!!!!
That essay on the Swift contains an aweful lot of hot air - if you'll excuse the pun :)
Ehem.......n/a engines do not rely on air pressure to fill the cylinders, they rely on the suction created by the downward stroke of the piston on the induction cylce. That is why any type of removal of a restriction will generally work well providing there is sufficient exhaust flow to cope.
Regarding the exhaust, generally the lower the back pressure the better in n/a, turbo or supercharged applications. In a turbocharged car there should be minimal back pressure between the exhaust valve and the turbocharger as this restriction is basically lost energy which translates to higher cylinder temperatures, lower boost and slower spool up time. There will always be some back pressure here because the turbocharger itself creates a restriction, but that is the only form up restriction you should have if possible.
Supercharged, turbocharged and n/a engines all benefit from having correctly tuned exhaust pipe dimensions. Who remembers the glorious Formula 1 turbo engines with their amazing tuned exhaust manifolds? Fantastic stuff!! The main reason that they are not in common use is due to the cost and space implications (and some people don't know how to make them).
If the pipe diameters are too large the gas speed slows down which loses torque - nothing to do with too much air flow as mentioned in the Swift. If the pipe diamter is too small there will be a restriction. A good ananalgy is blowing down a straw and a drainpipe. The air esapes from the straw very quickly, but you won't even feel it out of the downpipe becuase the gas speed is too slow. The pipe lengths are critical due to the reversion pulses that exist and can be used to scavenge and various rpm's
The manifold we have made has the correct lengths and diameters to suit the is200. Sadly it is a complex design (as you will see when I post some pictures) which means that it ain't gonna be cheap :(
That's burt up a few minutes - better get back to work :)