In reading up on all the many posts here about disc conversions, I see multiple postings that suggest removing the residual valve from the original M/C, AS WELL as adding a 2 lb and 10 lb valve if retaining rear drums..... My question is, isn't this a redundancy? or an extra step, for at least one of the valves that is being added? If the residual pressure valve in the MC is 2lbs....   why not then just leave it in, and then go ahead and add ONLY a roughly 8lb-10lb valve to the rear?