[DavidG]

A worthwhile tip given to me by an experienced auto upholsterer was that to ensure that all of the loops are equidistant from the headlining fabric when tacked or stapled to the wood bows, insert a sturdy, but flexible non-ferrous rod such as a welding rod through the loops from side to side and tack or staple the loop immediately beneath the inserted rod. If there is any disparity in the loop installed lengths you run the risk of puckers in the headlining.