i was looking at these on stangnets partshopper, and there are two for the 99-04 GT.
http://www.partshopper.com/fordmust...EST4-978B-DF8EAC622E79}&ic=MAC-PC9900&eq=&Tp=
this one that says it is to be used w/ the stock headers or shorty headers
&
http://www.partshopper.com/fordmust...EST4-978B-DF8EAC622E79}&ic=MAC-PC4900&eq=&Tp=
this one that is for long tubes.
if i plan to get long tubes in the long run, but not immediatly im guessing you cant use the LTBs prochamber on the stock headers?
http://www.partshopper.com/fordmust...EST4-978B-DF8EAC622E79}&ic=MAC-PC9900&eq=&Tp=
this one that says it is to be used w/ the stock headers or shorty headers
&
http://www.partshopper.com/fordmust...EST4-978B-DF8EAC622E79}&ic=MAC-PC4900&eq=&Tp=
this one that is for long tubes.
if i plan to get long tubes in the long run, but not immediatly im guessing you cant use the LTBs prochamber on the stock headers?