I've been trying to decide on Feuling 525 or S&S 509 cams for my 00 Ultra Classic upgrades. I've read multiple threads on multiple forums and peoples happiness with either set of cams seem pretty balanced.

I came across these dyno sheets at Rollies, my question is what causes that larger dip with the 509 cams in that 2500-4000 range?

S&S 509:
https://rolliesspeedshop.com/dyno_ch...-ss-509g-cams/





Feuling 525:

https://rolliesspeedshop.com/dyno_ch...ling-525-cams/

 

That midrange dip is usually caused by exhaust. I dont see mention of what pipe was used and if the same on each dyno but some pipes react differently to cams or overall builds. Now that Im older I tend to not look at the peak power numbers and more the average hp/tq in the rpm range I ride in, the more flat the torque curve the better IMO

 

The 509 bike had slip on mufflers, 525 had Samson 2 into 2 pipes