I've got the racing bullits with an offroad H in my 68 and would only change for the macs. The bullits are loud, but not nasty. The macs are chambered, but not so hollow-metallic sounding as flowmasters. Both will drone if you use turn downs and don't either exit the side or through tailpipes. I've heard an x-chamber and regular type x, and the chamber is a little toned down. Both had the bassani's after the x. Gutting out the cats will be better, but I think it might be like the x-chamber in that it will be toned down compared to an offroad H. You won't be truly happy till you can get one. I would recommend spending the time to gut the cats on an odd-job to raise money for the offroad. The macs aren't much more than the bullits and would go with the genre of the 5.0. My .02 worth.