You do not need a chip. You'll need a shorter mid-pipe, whether 'H' or 'X', and you'll need MIL's and O2 sensor extentions. I believe that a chip is beneficial, though, because it can be set to "ignore?" the MIL's. I have the listed mods and did not add a chip. I DO occasionally get a SES light. Easy to take care of, though. Just disconnect the battery for about 10 minutes and reconnect. It resets the reading and the SES light goes out. It seems the aftermarket MIL's will cause errors from time-to-time. Any time I get them wet (driving through puddles/standing water), I get the SES light. Car runs just fine with the light on, so don't panic. Hope this helps.
A chip is not needed with LT's. I've read people running lean sometimes with the addition of LT's but that's on a once in a while individual basis. A chip is very beneficial once you've done all of your mods on the intake and exhaust and looking to tie it all together and get every bit of hp/trq from your ride.