Like many, I've ARs built from PSA kits. To me the PSA kits provide the best values for AR type rifles / pistols. Except the trigger groups, which aren't good, and I replace them with something better - the PSA Nickel / Boron 2-stage is also a great value on sale for $70 or so. The Colt AR had a lousy trigger too. I've wondered, for those who use these kits, are there any other parts you think ought to be replaced? If so, which and why?