which bec suitable for 1/8 buggy?

I usually play 1/8 buggy in lali. But already two times my esc broken(150a). So I will try add external bec. which amp ok? 10a? 20a? for 4s battery. anybody use now? Thx in advance.

Castle 10A bec is ok Try adding a receiver cap on the receiver side especially u're using spektrum DSM1 receivers

If u know your esc broke down because of esc?  I assume you run powerful servo?  Try to add a capacitor first...
Castle bec is good... ESP if u hv castle link.

I just use savox 1258. it's not high volatage servo. Thx for the advise.

i also use 1258servo with dsm just ok at all....maybe not cause by the bec......maybe check the gear ratio sin....

hobbywing n toro 150a esc. some say these brand inside bec are easy to damage. So I want to try add bec.

First of all you need to make sure what cause your ESC to fail. There are loads of ppl running with HW 150A without any problem but you said it failed a lot of times in your system. Which means either you have very bad luck or something wrong with your car's drive train.  
So can your share you racing setup like what car? What motor?  motor pinion? Spur gear? No. of cell?  

I play team c t8e, tenshock 2100kv, team c 1900kv, pinion usually 15~17t. I use shorty battery.

1258 dosnt draw that much power ... should be fine with Xerun ..

Any binding?

only 1 servo and amb. thats all

Did you change any setting of the esc? like timing, punch etc?

not really.