Question says it all.....

What is the best brake master cylinder which will fit my 1989 si?

 

you should be able to use any civic 7/8 master cylinder for 88-91, possibly from more years too.

to upgrade it, get the 15/16 master cylinder used in the ex & integras. you may need to upgrade the brake booster to a matching unit however.

eric

 

The 90-91 EX is plug and play.

 

1" MC fits...i got it in my EF9

 

what's a 1" master cylinder out of? did you use a different booster?

 

yes did you use a different booster