I know this subject has been covered alot but I just had an interesting observation with my car. I have recently been getting my car ready to have my girlfriend in it, make it ride a bit smoother, fix the exhaust smell, etc. So yesterday I retuned my carbs and finished sealing up the area around my fuel cell. Before yesterday, I got very mild fumes and I figured they were coming from the rear of my cell where there was about a half inch by 7 inch gap. However, Once I sealed up that hole, I seem to be getting more fumes in the car. At first I thought it was that I might have improperly tuned the car and im just getting more pungent fumes, but it also feels warmer in the car especially in the rear as if from the heat of the exhaust. My hatch seal has never been too good, but now im pretty sure the rear floor of the car is pretty well sealed. What I think happened is that there always was a low pressure area in the rear of the car, and when there was a gap at the cell, it could suck in the cooler, non exhaust-y air. Now that I have sealed up those holes, it seems that the only place for the pressure differential to try to balance out is the rear hatch seal and probably the taillights. This led me to think that there are three possible solutions, completely seal the rear of the car, move the exhaust outlet so it exits out the side or somewhere else, or put in a port for the car to draw in cool clean high pressure air. What do you guys think of my hypothesis?