They will absolutely interfere with the headers.
Spoke to TTI about 5 times (Charlie I believe) and they basically stated if you want any of their headers you need to put the stock idler and pitman arm back on. So that's why I went with the hedman ceramic coated headers, would have loved to get the 2" headers but I didn't want to take the change of buying a $1K header and then chopping it up.
They also will not make custom headers for you, sad to say....
B