I bought the Logitech G27 wheel/pedal set about three weeks ago. I had Logitech Driving Force Pro wheel/pedal set. The brake pedal is too hard for me to step on. The pedals are too close together. Real cars usually have power brakes. I search the Internet for G25/G27 mods and the only mods are to make the brake pedal harder to step on. I also have Microsoft XBOX 360 wheel/pedal set for my MS XBOX 360 console and its pedals have light springs. Is it possible to mod the brake pedal so that it's easier to step on as the gas pedal?

Though I have to disagree with your opinion, as I'm sure most sim racers will, I think that what you want is quite easy to do.

I don't own a G27, rather a G25, but I assume the pedal design is somewhat similar. I've experimented a bit with the springs in my pedals, they are not difficult to remove or replace. I can't say where you would get a new spring, though. The springs aren't anything exotic, but you need something that has 4-5 inches of travel and is comparable in size.

I suggest taking the brake pedal apart(it's only a few parts) and taking a look at the spring.

You need this:

http://www.apelectrix.com/index.html

While the load cell does reduce pedal travel, you can calibrate it for however light you'd like to push.

Is it possible to get springs for gas pedal from Logitech and put them in the cylinders behind the brake and clutch pedals?

wear shoes, problem solved.

Quote from Calzone :

wear shoes, problem solved.

This, honestly, is the truth. Wearings shoes is a great first step, but just as important is what kind of seat you are using and what kind of angle your pedals are at in relation to that seat. In a rolling office chair, the brake pedal can be pretty hard to use.

Quote from bhs :

In a rolling office chair, the brake pedal can be pretty hard to use.

My G25 box is behind my chair, I can push as hard as I want. G25 pack gives all the facillities

I found out that I can place the pedals in any three sets of holes. I moved the clutch pedal to left set of holes.