my brother has a 66 Dart with the smaller tube TTI headers .
They are an ultra pain in the rear to install
I would imagine with Indy heads ( think they are physically bigger)…any header would be fun to install unless you hack the car up
I know the tti headers are a PIA . But they are nice when clearanced and installed. I always buy them raw ,then coat them after dimpling and break in . I did them on my 67 valiant .
