Z400 --- Torque Curve
 

Finally, somebody has published torque curves on this engine!! The Feb issue of ATV Rider (pg 19) has a dyno shootout of QUIET PIPES for the Z, and will have a shootout of performance pipes in the next issue. Mostly all you see are horsepower curves, which in my mind are pretty useless without the torque curve for comparison.

Anyway, the stock bike has PRETTY LAME TORQUE ON THE BOTTOM END, which just confirms what my seat of the pants experience has told me all along!!!. It maxes out at 23.7 ft-lbs @ 6000 rpm (so for hill climbing this is where you want to run). All the pipes make SIGNIFICANT IMPROVEMENTS IN LOW END TORQUE, but not so much on the high end. They average about 26 ft-lbs @ around 5,500 rpm. Looks like the Yoshimura (not surprising since it has a long history of working with Suzuki) full system comes out on top.

QUESTION--Do most of you run with a spark arrestor??? Here in Calif., you wouldn't dare leave your garage without one!! The reason I ask is that pipes often get tested without the spark arrestor, which doesn't reflect the real world for me.