I had ‘the fume problem’ on my 89 Plus 8, this originally had an 8 into 1 rear exit tailpipe, no fumes, changed to Librands twin system & that’s when the issue first occurred, on over-run mainly, under power it was fine. I experimented with airdeflectors, side exit tailpipes, spare wheel on & off, bumper on & off, mandrel bent angled ends experimenting in all directions, tried shorter, longer, filling the gap behind petrol tank area and rear of bodywork, no luck. Shenstone & District Car Club own Curborough Sprint & one of our members ran the wind tunnel at Mira (handy) he did alot of work with Morgan many years ago so knew the issues with barn door aerodynamics. From memory it’s all to with the low pressure area behind the windscreen ie the cockpit, if you can reduce it by bridging the gap between headrests it will almost cure the problem, I never did get around to making the final version but cardboard was too flimsy so Perspex was tried, it works, such a relatively simple solution. From what I can see so that’s 29 yrs to my knowledge that no-one has made an aftermarket solution, hint hint.
