Rolltigers24

I am getting into SCT and Buggy racing locally and am debating on purchasing the Losi 8ight or Team associated RTR to start and build/hop up as I go. Can both of these be upgraded to the equivalent of their Roller or KIT versions? Which one has the most build ability? Is there a list of all possible upgrades I can find? Also, can someone tell me some of the best sites To get hop ups? Any help is appreciate. Thanks, proud to be getting into the hobby, u guys are great