Since I'm in need of both front & rear brakes at the current time I'm researching this currently & should have some results or findings in the next week or so.
What I know so far.
Vehicles which use the 5*120mm pattern are: 2006-14 Ridgeline, 2008-13 Acura MDX, 2009-14 Pilot, 2005-12 Odysesy & possibly current (13,14,15) more research required. So to answer the question "I have an '08 Ridgeline do I need an '08 MDX, NO, any of the years listed will work, this is an interchangeable part over these years. A 2006 Ridgeline & a 2014 are the same, as is a 2008 MDX and a 2013 as is a 2009-14 Pilot, and actually if you own a 2008-13 MDX the Pilot Rotors & Pads are the same part number (only validated on one site)
Of all the options the Ridgeline rears are the largest production rear disc brakes that Honda installed (currently validated on just one site). The fronts are largest on the MDX & Pilot, although by the numbers I've found I'm unsure if the costs are really worth it, especially since I haven't found the part numbers to answer my final questions.
So if someone owns one of the other vehicles MDX or Pilot, or has done this upgrade, is the bracket which holds the caliper the same? Can I use my Ridgeline bracket to bolt the Pilot/MDX caliper or is the bracket bolt pattern the same and that where the transition occurs?
Meaning buy the bracket, & calipers for either from anywhere, new, used(junk yard) or reman from a typical parts store. Then purchase rotors & pads, your choice from, stock replacements, to EBay or parts store brand, or EBC, Hawk, or Akebono, to name a few, and your off to the races.
Once I've validated the rotor sizes on a second site I'll post everything, I'm hoping to have info together later this week.
My only other thoughts are, I know others have put BMW wheels on their Ridgeline so there may be a possibility there, but, just guessing very cost prohibitive, and probably only available for the fronts, although that may make a brand like Brembo or other brands may be available.