My only knowledge of them is a T&T dyno article comparing EDC, Peacemaker, Basani, Hooker & std Yam pipes on a std RT3. I've never used one but T&T concluded it won on both performance & low noise:
"The object was to find the best pipe for the serious trail-cum-enduro rider. This meant weighing up flexibility against top-end against noise against price... there can be no doubt about the winner. EDC pipe is number one by a mile... It has the most power down low, mid range, & up top"
It peaked at 6000rpm & dropped away quickly after that, but made more horses at 6000 than the US pipes did at 7000 (their peak). MUCH better in mid range, in fact from 3000 to 6500.
Only thing it was rather fat in mid-section