looks like about 10 HP, maybe would have pulled longer if it didnt have a rev limiter.

 

It has a dyno chart, on the adobe acrobat page on the site, about 8-10HP I also got a 2001 Rocky Mtn ATV Catalog that lists the DMC Pipe for the Raptor as part # 25-047-00 for $476.99. hope this helps.

 

No we don't know the HP gain! Those charts are not for the Raptor. Stock Raptor HP peaks at 6500 RPM. Those charts are for a banshee.

 

Dude click on the right where it shows the dirtwheels page ad. Let adobe acrobat load. look at the lower right it has 2 charts HP and Torque. ANd It says Yamaha Raptor 660 under it. use the MAgnifying glass and look. now open the other page with the banshee, it is flat and then hits power at 6k, where the raptor pulls a gentle slope from 3K up to a similar slope, This is why the Raptor has a Banshee Feel and still has a low end.

 

I did look at the pdf file. Those charts are for a banshee although they say 660R. Compare the raptor stock dyno run that has been posted to these charts and you will see what I'm talking about.