Dynomax VT mufflers

Tom My engine is 500 cubes, and the cam is 236/242 duration so it has a noticeable idle. I currently have the super turbos with no crossover. I will be adding an H pipe when I install the mufflers. My car is street/strip and I thought that these would be a good compromise with relatively quiet cruising and pretty much straight through at the strip. I talked to their tech line and I was going to order 2 of their 17956 mufflers designed for over 4 L engines, since mine specs out at 8.2 L. Apparently they run a stronger flapper spring.

Rumble, I am looking for that same size and offset. Do you know what part number yours are? So you feel the super turbos are quieter in normal cruising?