I've used 17748, the 2.5" version on my 2005 5.7 Hemi Magnum.

*It's important to differentiate between the short case one that usually drones, and the long 20" case model that usually doesn't.

The car had no cats and an H pipe, so very similar to an older car in that regard.

I loved them, they were just right for a good, throaty sounding driver that was never annoying.
Long distance drives, 3-5 hours, no problem at all.

They do not flow well. The car felt faster with 2 chamber flowmasters, and even those don't flow well.

But they do keep the car pretty quiet and sounding good.

I feel they are a little too quiet for an occasional short distance Hellraiser kind of a car which is why they make the race bullets and the ultra flo.