I've cracked it trying once, but you could get a dremel and cut the black piece in sections and try to snap off the sections. I'd just buy a new one. I got a 35th anniversay one for $18 at the dealer back in the day for my 99 mustang
I have one friend with Moser and one with Strange. They have had them for years without trouble launching on drag radials. I don't think you can go wrong either way. Good luck.
I hate changing the plugs especially since I am a victim of shoting a spark plug out of the head. I wouldn't use that stuff if you need to change the plugs. Leave it alone.
When I went from stock h-pipe to high flow cat x-pipe, it sounded a little better. When I went from that to off road x-pipe, I feel in love with my car again. My dealer never said a word about the pipe. I never felt a differnce with the pipe though.