Since my car is pretty stock and I have no intentions to upgrade/install anything, here is a write up how to kill some time and clean your stock muffler tips:
For this DIY I have used :3M Scotch-Brite Heavy-Duty Scrub Sponge $3 and Bar Keeper's Friend 10046 Cleanser and Polish $5
The directions are straight forward:
1. On wet sponge (yellow side) put some powder and rub until it shines.
2. Rinse after the desired effect is reached
NOTE: Using the green side of the sponge will leave some micro scratch marks