What should i do, I still have the original exaust soon to be changed out, but when I drive the car for more than 5min, the inside of the car starts to smell like exaust really bad, I was wondering if it was a bad cat back( i checked the rest of the piping and its fine), or im thinkin could it be the taillights wher the exaust might be seeping in. thnxs for the help in advance*

 

More than likely the problem is under your hood. Start your car and let it idle. Take your hand and hold it just above the valve cover on the injector side. If you feel puffs of air, your gasket is shot. Also, you might see some black streaking on that side of the valve cover that will wipe right off.

You might want to look at your injectors while it's running too. When they start to seep gas it stinks pretty bad.

Just a couple of things to look at.

 

Also check to see if there has been any welding done to the exhaust on the underside of the car that could have cracked, look for black on the piping. I had my exhaust crack on me just before the cat and it made its way into the passenger compartment. And when I replaced my muffler I just used clamps instead of welding it and it started leaking into the car too. Both would make my eyes water pretty bad if I didn't keep the windows down all the way.