I got a borla cat back exhaust system and it gives a good hum to the car, but i want something louder so i can be heard. Ideas?

 

Remove resonators.

 

In what muffler or holo out the cat?

 

Why do you need to be loud? You won't go any faster, and may just wind up annoying your neighbours. It's the same with loud pipes on motorcycles. They don't really improve performance and just tick people off (and I ride, a lot, and do have after market exhaust on the bike, but it isn't obnoxious).