Gareth,  You will definitely want headers that tuck up tighter to the frame/belly pan and some brands of full-length headers are much better than others in that way.  I replaced a 40  year-old set of full-length headers of unknown brand that had been severely massaged to fit with a pair of Patriot "shorties" and ran into ground clearance problems big time on the driver's side with stock front suspension.  So, even shorties may not tuck under without modifications. Not sure why but the