I would run manifolds before TTI headers. It’s that simple. IMO they are junk and there are better options. If you are smashing your headers flat it’s because you have issues driving the car with headers.
Better options then tti? You have two choices tti or Doug's. No better options. If you are smashing headers it's because you are most likely running low hanging garbage hooker, headman, flowtech or any other of those cheap *** pile of **** headers that hang low and block plugs because of a poor design.