You have to be carefull what you get for XT. They have a 350FPS limit, so a super upgraded gun my take you over that.
If you are interested in outdoor stuff, check out the Manitoba Airsoft Association @ http://mb-airsoft.com
There are lots of games that are new player friendly. Field limits are 400 AEG - 470 for snipers (semi only MED of 60 feet min) Some games allow under 18s to play.
And when you turn 18 in July you can talk to AMOS about getting age verified for the MAA and ASC.