possible vacum leak???

[hondakid4dr]

yesterday im driving and all of a sudden i notice a lost in power from 3rd gear and up at all rpm ranges...and i hear like a whistling sound and i can tell were it coming from i dont think its an exahsut leak cuz i went to emmisons 2 dayz ago...also my car doesnt sound as loud as usual it sound light any idead sum1 please????

[hondakid4dr]

if my headers were cracked any1 kno if that would affect performance as well