You have to either modify the Z-Bar or buy a TTI Z-Bar otherwise you will have this issue. Check the thread below, it has the modification directions. This is mandatory for Doug's or TTI long tube headers.
Modified Z-bar for Doug's Headers (pic)
Or buy this. The first picture in the link is the B-Body one, the second picture is correct.
TTI A Engine Z-Bar
I have Doug's headers and the TTI Z Bar. They cleared both my A833 and now my TKO. Its tight, a later 80's, early 90'd Magnum based mini starter helps.
