On my sons 72 Dart with a 400 we use the 2" CPPA chassis headers which I bought in 1996 before TTI was out but I believe TTI are the same. His are not a problem as only one plug is a little tight which is not bad as I can change the plugs in 15 minutes as long as the eng is cold. His is all stock with the torsion bars. We installed them by dropping the K-frame and putting them on the eng while the eng and trans were bolted in the K-frame and then lowered the car down over it. Really the only tight problem is the starter. Its never gone bad but if it does I think we would have to loosen the header on that side to get it out. Ron