Recently I cut off my exhaust just before the Y and welded on some thrush glass packs and dumped them right after the mufflers. I have 35" tires and have no problem keeping her at 80mph at around 2,400rpm. Before I did this she would have to stay in the passing gear just to maintain speed. I am worried I don't have enough back pressure now and that my low end torque is suffering. Does anyone have any suggestions?