so thatīs 10hp from a untrustworthy vendor on a car with what mods?
this dyno chart from a forum member with a stillen pulley seems more in line with the gains youīd expect from a crank pulley swap. I donīt even think Iīd bother to turn a wrench for 3hp.
edit: for the full review
Stillen Underdrive Pulley - Review/Pics/Dyno/Vid