Exh ????
You are running CATS and a LM, but that doesn't mean rasp. The LS1 is a different engine to other SBC and thusly sounds different. I have a LM and it certainly isn't raspy at all, maybe your cam is affecting it more.
You may want to look at swapping in a Borla XR1 or my preferred choice a Magnaflow bullet.
Both of these will change the tone but probably not the volume. If you really don't like the LM then changing it for a different catback or duals is probably your best bet.




