[Big Block Bill]

Just a thought, does this smell happen with all brands / grades of fuel? Some lead free fuels have a lot of ethanol in them which can be causing your smell. If you can, get some, (because you stated you do not have converters on it) leaded Racing fuel (like Cam-2) just to see if it makes any difference. If that does not change anything, then I would have to agree with everyone else that the exhaust exits needs to be modified. Good luck.

Bill