Conner... If you plan on running the C3 in the trunk, i seriously doubt you will ever even hear it... You have to be looking for it... In mine and ignore's cases we both are just Meticulous about detail.... Thats the first thing i did when i got them running.. I lowered the volume played tones from 27 to 45 and stuck my ear up to them.... they were quiet.... They started making that noise about 10 hours hours after that... Now at about a month and a half it has almost gone completely away...
Also in the vehicles we run they never were in the trunk... So the chance oif hearing it increased.. i never heard it up front at all... Just when i was close to them with the hatch door open...