Oil smoke

Now I havent had this problem until I put a dynomax ultra-flo on my car with no cat. Ill be slowing down from a highway speed and Ill notice a smell of fluid. Now the other day I saw that it was bluish gray such as oil is coming out of the tailpipe. I was told that when slowing down, there is no pressure in the cylinder and oil get burned. Since there is no back pressure, it only helps the oil get sent out. It didnt do this when I had a flowmaster on the car. I was also told I may need new rings. When I put the motor in, it had a rebuild sticker on it and everything looked fairly new even though the car sat for at least a year. Any comments? Thanks

It also does it like at a stop light if I rev it and a few seconds later it will smoke. I was thinking it was the valve seals. I dunno if it does it on start up and yes the car did sit for over a year in southern Missourri.

The car has been up and running for two years. I am just going to replace them, theyre ten dollars for some fel-pro ones.