I called the popular online parts vendors, told them I was going to make 50oFt.Lbs. and needed a full clutch kit for Road racing/autocross. I acquired recommendations and listened to guys at this website rave about this clutch and so I went with a Zoom HP48-1S. It's rated for 500FtLbs. There is a 90 day warranty. I also purchased a new Fidanza aluminum (zero balanced) flywheel. So, I have all new goodies, no corners cut, no expense spared. New engine dyno'd at 460HP/TQ... so, I should have a good match on the clutch. After the installation of engine, tranny, headers, supports, etc, etc, etc. I only have 300 miles on the rig and she's slipping bad on hard shifts (up & down). Thank god for Rev Limiters Called online Vendor, they put me onto Zoom Mfg reps. Zoom reps recommend I burn in clutch for 500-700 miles. I only put 1,000 miles on this rig annually. So, the bottom line is that this clutch DOES NOT hold up to 500ft.lbs. as advertised -and- I'm not going to tolerate driving this rig with an egg under my foot for 100 miles, much less 500-700 !!! When Ford, Chevy, or dodge sells you a ride with 400+ HP, they don't tell you that slipping will occur for the first 500-700 miles. In short, I'm going to tolerate this slipping until it's cool enough in my garage to put in several hours of effort to get this paper weight out and put a button clutch in. I'm also going to call the Online Vendor as they're supposed to honor the 90 day warranty. I can only hope that with the stupid $$$ I've given them over the years, that my grievance carries weight to my satisfaction. In short --- Zoom has disappointed me here.