8.8 IRS upgrade questions

[Ace23]

Finishing up our work on my Superformance. My car has the 8.8 ford differential. The diff is out and we are ready to drop it off for the gear swap. I contacted the driveshaft shop in NC and elected not to go with a 31 spline upgrade. I am instead having them build me a set of their level five 28 spline replacements. The stock half shafts may have lived but I did not want to have to worry about them. We are running a 427 Windsor with a 6-speed, upgraded rear gear and drag radials. Strictly just a street car with a little twist to it.

1. Is the stock differential cover okay or is it a good idea to upgrade while out of the car. If it needs to be replaced please explain the reasoning.

2. Craig's cobras offers solid diff mounts....we noticed poly diff mounts are also available. Has anyone had experience with either? I've read somewhere that the aluminum mounts can create noise.....with 3" sidepipes in an open roadster is this really noticeable? The main reasoning behind the use of the solid mounts are to avoid wheel hop.