I just got back in to carpet racing within the past year and went with Xray. You cant beat their manual for setup information and explanations, plus there are a whole treasure trove of videos on YouTube for the cars. They are expensive, but if you go the used route instead of the latest and greatest you can save quite a bit. I run 2021 T4's and have learned so much from the guys who used to race them and watching Alexander Hagberg's videos.