the TC7 caster blocks were a bit stronger for me as i wasnt snapping them anymore. they fit w/ the 6.1 steering blocks with a little bit of shaving on the upper portion of the TC7 caster blocks. aside from that if you 'must' upgrade, i'd only recommend reflex short shock towers and tc7 shocks (tc7.1 will probably work as well but i know they're supposedly shorter than the tc7)