Jason,

The nice thing about having Hatori and Macs available is that you can use the brand that is best suited to the engine. Although not exclusively, Hatori specifically makes (made, in the case of 2c) pipes for YS engines, so they should work well.

Also, if you are going to build a Japanese classic, then YS/Hatori is kinda cool to do. On the other hand, if you are going to build an American Classic, then Jett and Macs is the honorable thing. In the case of a European classic (e.g., the Arrow), one could go Rossi/Webra/ST engine & OPS/Webra pipe.

Of course, in the real world we're not such purists...

David.