I have a 2006 Colorado with the I-5. I know the tow rating is 4,000 lbs. but I am interested in experiences of current or past Colorado owners. - How much weight have you towed with the I-5? - Do you use electric brakes on the trailor? - Do you have any additional modifications done in order to tow? I am looking at towing a Camaro to the racetrack on an open 18' trailor. Any help would be appreciated.