The machine that Krusty put up is a nice version of an on/off road set up for a 4... downswept exhaust is sensible when you consider that at some point that a heavy engine with upswept hot pipes could be laying across your leg.
I had this hankering for a little more serious 550 dirt conversion once
http://forums.sohc4.net/index.php?topic=124957.msg1419721#msg1419721it could have worked, I suppose...but after the mock up, it was obviously going to be a disaster looking for a place to happen.
I guess what I'm saying is... that sometimes when we concentrate on making a questionable/unusual modification idea a reality, we overlook the idea that someone else has thought the same idea, implemented it, and found it to be either too dangerous, a big PITA, or an out and out failure.
Quite possibly the reason that the CL pipes were never stock on an inline 4, but you can't deny credit to to a man with a vision and the will to see it through.
Matt made that cl 550 four look badass didn't he?