[Formulajones]

Regarding the over the axle tubes, that's the only issue I have with those Flowmaster transverse kits.
They have the inlet pipes entering the top of the transverse muffler, rather than the typical side entrance. This creates an axle tube clearance problem even on a stock rearend, making it necessary to mount the muffler as high as possible, and sometimes that's not enough. It also keeps you from being able to tilt the muffler as needed for tank and rear end clearance.

If you use the Pypes transverse system, or the Dynomax transverse system, they still use the OEM style side entrance for the over the axle pipes, and as such they can be bent to follow the contour of the rearend floor tunnel much more closely giving more clearance.

I've used them with aftermarket Strange 12 bolts, 33 spline axles with larger than stock axle tubes and they work with ample room.