This past weekend I had the opportunity to race several bikes,many times, on pavement and dirt roads, to evaluate the engine performance of my Z. My DRZ400E has been jetted, 165 main, pilot and needle raised. The airbox snorkle is removed and exhaust is stock. Gearing is stock E (14/47). 3)XR600's - Friends of mine. All had stock exhaust pipes with the cleanout plug removed and one had a Thumper exhaust tip. Another one had lowered the countershaft sprocket one tooth. We ran several times from 40,50, 60mph to max. I suspected I was faster in midrange but they would get me at, or near, the top end. Nope! I pulled them all to max (at 87mph I hit the rev. limiter)and none could catch me. The one with the Thumper paced me at top end but I was 6-8 bike lengths ahead and he could not gain ground. When we switched bikes I remembered what I liked about my 600. It really pulls nice from down low. But, when I downsized from 600 to 400 that's all I gave up. WR426 - Throttle stop removed, air box snorkel removed with stock exhaust and jetting. Same as above but he accelerated better than the Honda XR600s. From 60mph roll I jumped him 2 bike lengths right away. I pulled him on top by 2-3mph. We switched bikes later on the trails and he commented on the good low end and nice hit mid to high on the Z. I thought his suspension was better. Nice on the little stuff but much better and confidence building on the larger stuff. I'm still not sold on the DRZ suspension. DRZ400E - With air box snorkel, stock jetting and stock exhaust. We were very close. I was a little faster on top and a wee tad stronger getting there. At times our acceleration was even. Surprised me! He did complain about hesitations when it was cool out. The box stock Z would beat the XR's and WR. Naturally I was feeling on top of the world. Man this Z really rips. Then my friend with the WR426 had a problem with the exhaust tip and had to remove it. Ah Oh. Yep. He was faster everywhere. Out accelerated me and on top, while I was surging against the rev. limiter, he just kept on walking away from me. Oh well. Quiet against quiet the Z rules. Now I wonder what it will be like when he gets the jetting right?