get the lunsfords if you can find them.
i have gradually swop out the stock kyosho turnbuckles with the B4 blue ones, as/when the stock turnbuckles bent or break.
so after 20 mths, my car has a mixture of black stock turnbuckles with blue ones ..
but my used-zx5 came with lunsfords and they are visibly a lot beefier than the B4 titnium turnbuckles.
IF you decide to use the B4 turnbuckles, make sure you use a fresh pair of ball cups too because the thread is different (as explained by someone earlier).