You want a motor faster than a 3.5
I think SpeedPassion do a 2.5 but I can't think why anyone but Hara/Andy Moore etc... would want it!
Your FT TC4 could easily handle any motor that you chuck at it. Altough not to everyones taste it's a competitive car that can be driven as quickly as any of the current crop of cars. If you want a new car for the sake of it the new Tamiya 416 looks very nice as does the Xray T2 008.
I don't know whether these cars would fit your lipo though.