I previously purchased new 2008, 2011 and 2012 Impala LTZ models. On each one, I added chrome exhaust tips which were very nice and high quality. They were sold by the dealer as a GM accessory.
I’m not sure if they are still made, but you can do an internet search. I no longer have the part number (they came in a box of two tips).
If you buy them, the instructions say to cut off the end of the existing exhaust outlet. I did not do that on any of the three models I installed them on. They simply slipped on the existing exhaust outlet, and then were fastened with a high-quality stainless clamp (two were included with the kit).
Fwiw, with most tips you shouldn't have to cut the pipes. Just slide the tips over the pipes to the desired length/exposure. If necessary, just tap them on/over with a rubber hammer/mallet. Mine are flush with the bumper to avoid bangin' shins, lol.
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