Swapping Test Pipes and HFC re-tune?
 

Pretty new to the forum and Z modding. My question today is if I were to put test pipes on my Z and swapped them back to High Flow Cat's I assume I would need to re-tune my car, am I correct? and if I didn't what would happen? I plan on doing my mods in this order probably not all at once. Exhaust, HFC or Test Pipes maybe both so I can be legal when I want to be (swap them out), and then do Headers at some point. Would it be silly to swap out the Cat's every now and then or do you typically do one or the other and stick with it?
Thanks