I can’t speak for slot cars but as far as rc cars it has been less then desirable. They know what parts do what but lack the understanding of if it will fit or if it can work in your cars frame. I would go back to order specific parts but I can’t rely on their recommendations for anything except Traxxis. Granted its really easy for Traxxis and as a local shop you would expect them to be more knowledgeable of these things. So overall if its about anything Traxxis, good. Anything else and results can be questionable.