How much to replace Exhaust pipe in 07 Nissan Altima 2.5SL

Hello, the exhaust pipe is quite unlikely to be the cause of your power loss. Diagnostic testing is required -- this may or may not be related to your roaring and rumbling sound, but would be the right place to start. Trying to find the price of a guessed at repair that likely has no bearing on your problem won't do much to help you, I'm sorry.