Doug Thorley Headers with SB Trick Flow Heads

Somethings going on here and I dont think its the heads. I had edlebrocks and trickflows and j heads and the headers were always in the same place. Now the cars themselves are a nightmare as far as production tolerances.

On my four speed duster with dougs headers and the correct tti z bar there was no room to spare but the z bar cleared.

Now my four speed dart with dougs headers and tti z bar would not work and I had to bend the z bar a fair amount but in both cases the headers were identical in relation to the steering box and t bars?,fun stuff.

Both cars had spool mount k frames and both cars were within a 1/16 of an inch of ttis measurements.If you have not checked those measurements that is the first thing that needs to be done.
http://www.ttiexhaust.com/PDF/II_TTI636A.pdf