ss hydraulic hp?

[tnmtn]

hello all,
looking for some help on what hp size skid steer would be required to run an attachment that requires 23 gpm hydraulic flow. i have seen where the manufacturers show what their aux. flow is, but was not sure if that was a max number or included power leftover enough to move the skid steer while pushing the flow. any help on this would be appreciated.
thanks,
metin

[tnmtn]

if this helps any this is the attachment i am looking at. http://www.gyrotrac.net/skidsteer/ . it says its low flow but most mulchers seem to need high flow. just looking at diffrent options at this point.
thanks,
metin