That is true. The exhaust flange on a Mopar is angled slightly so if you're building custom headers you have to decide if you want the tubes to be perpendicular to the flange or if you want to have the tubes continue the flow. The cheap and easy way to make headers is to make them perpendicular but that might not be the best way on a Mopar. The dyno headers I use have the tubes coming out of the flanges at a slight angle. Those headers really work well but I can't say they are the "most perfect headers ever". I've done my share of header testing and most of the stuff I see kills power but sometimes you'll find something that actually works pretty well. Schoenfeld dyno headers usually make really good power but of course none of them fit in a car. https://www.schoenfeldheaders.com/sprintdyno1.html