I'm running a CL350, with straight exhaust, without any adverse effects, I'm using a 117.5 main jet with the straight-pull SL350 carbs. FYI im at an altitude of around 4500 ft. I have superb power above 4000 rpm and moderate power up to 4000 rpm....I say go for it, the stock exhaust is clunky, heavy, and mostly rusted through after nearly 40 years, make it an artistic project...make it unique...make it your, not old man Honda's!