Dear Mr. Bane;
The "X pipe" (theory) may work on the larger (400+ CID) V-8 engines, because they have a larger volume/number of exhaust pulses in a different configuration. There is some 'dyno data' to support it, but little.
This was developed so the EPA wouldn't ban "straight through" mufflers in their fight against 'noise polution'. I think GM put it on the Corvette to keep noise down too.
Our inline 6 engines have none of this to consider and history has shown that an "equlizer" defeats the purpose of headers on them.
In the 1950s Muffler Shops created this as a "quick fix" to traffic tickets for loud pipes etc.
