for some its for personal satisfaction having a schuemann, barsto, etc.. installed..for some it makes them "shoot better" and for some only the best will do (should have gone the custom route though). I was like that when I was new to the sport. just had to have a barsto installed in my gun which had no accuracy problems.it was installed by bubba and runined the guns timing and perfect fit.. later on I realized barrels nowadays are well made.I once had a norinco. after a bit of tuning and hard fitting a bushing it shot 1 hole groups at 20m with the stock barrel..shot thousands of rounds never lost accuracy I later regretted selling it. I wanted to buy the gun back but adding insult to injury the new owner refused and thanked me for having the gun built the way it is.anyway back to the topic, if I had an sti id only change the barrel if I was to be competing with the top 10 GMs. STI barreled guns I have handled are very accurate..