strange that it only fits "cruisers".

The best way you can get maximum performance (without modifying the engine) is from an engine using a piggy (no matter who makes it) with a closed-loop system.

To close the loop on my ZX14, I'd need a PC with Autotune and O2 bung / sensor, set to learning mode.

They are right, though, in that article you linked. Many O2 bungs are in the wrong place. The O2 sensors we can buy/use are not fast enough to work anywhere near the exhaust header, because the exhaust gases produce shock waves which our cheap O2 sensors cannot handle. So they produce a lot of spurious readings.

This is why Brock puts his back closer to the mufflers, far enough from the collector, even, to get out of the shock waves. Even then, there are still pulses in the gas flow all the way to the mufflers. So Autotune is using the averages to make up for lack of precision from the O2 sensor.

In NASCAR they are just now, this year, for next season, going to an ECU which controls EVERYTHING. That way the judges can hook up to them and know exactly the state of tune being used, as well as a running history from before the race until the reading. They have an O2 sensor too, but that O2 sensor probably costs over $1,000 each, and is VERY fast.

For the C14, probably the best exhaust system is the Muzzy dual. It is very quiet, makes good HP, and is light. And it gets rid of that clunkly single muffler with a pair of nice ones. If I end up with that configuration on my C14, I'll put the bung back about a foot forward of the cans. Either side should be fine, because of how the collector is designed. Then I could hang a PC5 and Autotune, and go closed loop.