Any exhaust you install will only amplify the sound of Corolla's tiny engine so you'll actually have people impressed with the sound or laughing at it. Improving the performance is a matter of opinion. Personally, I'm happy with the sound and performance of my stock exhaust, so I'm keeping it for now. As for after markets, the TRD is one of the nicest looking ones in my opinion. You can also install it yourself since no welding is required. Some of the more popular brands are Borla, Magnaflow, Flow Master, and Apexi. There are tons of others. Just check YouTube. You can also get advice from your local muffler shop.