[hunter4ever12]

The exhaust seems to flow pretty good and I just did install a glass pack type muffler replacing the stock one. How would I check the flow of the exhaust to see if I have a restriction? Could I use a vacuum/pressure gauge and remove the O2 sensor and screw the fitting for the gauge in there to get a back pressure reading?

I do know the exhaust donut gaskets leak I added sea foam and after doing so and driving it there was a considerable amount of smoke coming from under the hood I opened it up and that's where it was coming from. Could that be an indication that my cat is possibly plugged (ie the smoke "backed up" and couldn't flow out the back so it came from the small exhaust leaks)