Thinking of purchasing a 2003 Regal LS, what are some common issues that come up with LS's with that much mileage? (one owner)

Yes. I did. My Dad bought a new 2004 Regal which became mine in 2011 when he gave it to me when he voluntarily quit driving at age 90. It had a lot of trivial things go wrong, break. Like the Glove box latch, window regulator, all of which I fixed. But that car was mechanically sound and one of the more powerful cars I have ever owned.If You don't want to buy it there are plenty of people that do. It has a stiff suspension, by design. Will out-corner most cars much more expensive. Just make sure the oil gets changed in supercharger, and it will go a long way. Sure wish I still had it.