I have tried multiple products for this and found very little satisfaction. I even tried a product made by Blue Coral (thinking that it must work if they put their name on it) and found it to do nothing more than make the blued pipes very shiny. This stuff works great as a chrome polish but didn't do the job on the pipes.
I have found the best way to fix the heat discolored chrome is to prevent it with a ceramic coating in the pipes. Cycle shack makes a very simple product that is cheap and easy to use called "Chrome Guard". I have used it in straight "drag pipes" without any carb adjustments from the stock mufflers and had no discoloration at all.