Hello I’ve been looking at some mufflers and I want to see if anyone had any issues with the check engine light? Was there any power loss? I just deleted the resonators and looking for a deeper throatier sound. I’m not looking to straight pipe it. I have a 97 sc400

 

You will not have any CEL issues with a better flowing muffler. Those only occur if you alter or remove cat converters.

You won't see a power loss however you might not experience a significant gain. You will notice a louder car, that is certain.
I don't think a muffler change will give you the sound you are after... but what will would be a custom built 3in exhaust with 3in flange aftermarket mufflers