Join Date: Jun 2008
Location: Steamboat Springs CO
Car Year: 04
Car Model: XT
STi Brake Booster Swap... A MUST DO!!!
So after an STi master cylinder, SS lines, Superblue fluid, front Brembos, rear H6, and HP+ pads I still wasn't happy. There were several times when the pedal had NO feedback at all. The only thing that the mush could be was either the lack of a rear Brembo kit (~$800) or the brake booster (used, $37.50 shipped). So, I bit the bullet and swapped in an '05 STi booster I bought off NASIOC.
Holy mother of crap! Night and day... If you drive hard or you've done a brake swap, you must to do this. Some people say that it doesn't do anything for performance, only pedal feel. Well, they haven't had their setup hit the floor then.
Yeah, it's a major PITA... but you simply have to do it. I had already swapped my master cylinder and bled it with fresh Superblue fluid so I didn't want to take it out. I was able to the swap WITHOUT taking it back out. Once it's unbolted it will move out of the way enough. There really isn't a trick to this... It's about as labor intensive (and rewarding) as swapping over a steering rack. A solid 3-4 hours if you know what you're doing.
Here are some tips...
-You need to put the actuator arm back over the brake pedal arm and put the pin in before you tighten down the booster to the firewall. If it's not on you won't be able to push the rod in enough to bring it down/around/on. That'll make sense when you're doing it.
-I siphoned the fluid out of and removed the clutch reservoir for more room. Just don't hit the clutch pedal with it off and you can reattach and fill the reservoir when you're done. No bleeding required.
That's pretty much it... If something seems to be in the way take it off. Off the top of my head, I removed the TMIC, air pump, a few vacuum lines, the TMIC mounting arm, and a bracket that holds a silver tube to the firewall.
Good luck! Go do this!