The mod you mention was SOP for probably 90% of Harley Davidson motor cycles through the mid 1990s. Simply insert a lenght of metal pipe up each of the exhaust pipes, bang away with a mallet and punch out the baffles. Worked great. Around 1996 HD introduced catalytic imbedded exhausts (along with fuel injection) which ended the practice.

I would not attempt this on my CS, but I'm as mod adverse on my cars as I'm mod friendy on my motor cycles.