TC on foams is definitely out of fashion, but is a lot of fun if you just want to do club racing and tyres are open. I run them indoors and outdoors at club level. Performance is better than rubber, more consistent over the life of the tyre, and tyres are cheaper.
You want nitro foams, I've been using Matrix from rcmart. Xceed (Enneti) from Amain also look good (I have some but haven't run them yet). The key thing to know is that fronts and rears are a different type of foam; the fronts are much denser with less grip. I tried running the 26mm fronts on the rear and the car was terrible. So you need the 30mm rears for the rear. You can either cut them down to 26mm, or maybe fit them on full width depending on your car. I've machined the rear arms on my Xray and dremelled the shock ends so I can run them full width.
Compound wise I run 37 rear and 35 front.
I run 4.5t mod indoors and the car is epic
Mine is the yellow and white one, running just behind the plain blue one at the start:
https://www.youtube.com/watch?v=nnrf...Y6kjX2RTYUnL2N
The drivers I'm racing with (Elliot Harper, Kyle Branson etc) are significantly better than me, but the tyres make up for it.