Hi Paul, I am using a device made by Leo Bodnar that lets you attach the pedals directly to your computer via USB.
here is a link to all his mods: http://simracing-mods.de/tags/leo-bodnar
(and you may find a link to his pages as well, or look for "Leo Bodnar pedal mod" in Google)
The main reason is that his device (used to be a box, but it's now integrated into a USB cable) increases the sample rate of the pots in the pedal set. So where before you had just less than 500 samples per second, now you have over a 1000 (I am making the numbers up).
Principally it's used to run the Load Cell mod that substitutes the spring and potentiometer assembly with a load cell, making the brake feel a lot more like a real brake pedal. In other words lets you brake by pressure rather than travel. I highly recommend it even just for a regular G25 set of pedals, but changing to a load cell makes people faster overnight. less locking, better brakes, faster laps.
Problem is that while serious sims can support up to 3 controllers (allowing me for instance to take an old PS2 style usb controller and place the buttons on my wheel as a third controller) GRID doesn't seem to support that.
Not that I will cry salty tears about it: I Have NKpro, rFactor, LFS and I usually race on iRacing, which overall is the best of the group. But I wanted to give GRID a spin. I guess I'll have to shelve it.