i have to agree. i had 3" to the bumper on my dart and when i had it running the best i could to my tuning abilites, had good free flowing mufflers with an X pipe. i pulled the exhaust off and tried rejetting it. and it didnt pick up anything. at all. i had a brain storm and thought i was going to detune it and built a 3" into 2 1/2" system with ultra flows and that alone killed it. i think the 3" exhaust was damn close to no restriction and if anything the 1 3/4 headers kept it from gaining when i pulled the exhaust off. it was way too loud inside for me to ever want to try it again. if you are ever going to look for the msot power you possibly can have with the pedal to the floor, your goign to want to go with 3" over the 2 1/2". if you dont think you will ever be in that situation :bs: , then go with the 2 1/2".