With my stock exhaust still on, how will the Crawford High-Flow cats effect the tone. No change at all? Big change? Noticable, but nothing to write home about?

I just don't want my car to sound like a pimped out Civic!

 

The tone of your exhaust will not change, it will be louder though.

 

Yeah, I like the tone of the car...stock. But louder? Wow.
I'm assuming "louder" is a relative term.

I'm assuming still quieter than if I decided to leave the stock cats
and get a Borla exhaust system?

 

I have both the Crawford CATs and Borla Td. The combo is not loud at all.
I would say the Borla increased overall loudness more than the HF cats did, over stock.