Even if my stock cat is in perfect working condition will I still get an increase in sound from using a high flow one?

 

The more flow the louder the sound. I went from stock exhaust with a flowmaster to slp heads high flow cat. It's really loud now, kinda annoying with the flowmaster. If you do decide to install a high flow cat and headers I wouldn't use a flowmaster. My car sounds like a hillbilly truck at idle, and at high rpm it make a sound like when I step on my cats tail.

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1988 L98
Vette Heads/no EGR
SLP Headers/Y-Pipe
ARAP bin