The '04 Comp's shock measurements are 8.75 i2i and 2.50 stroke, as for the '03 DH is 8.75 i2i and 2.75 stroke (I think), I'me certain about the size of the comp's though.
You cant fit a DHX 5 on a Comp however due to clearance issues, same thing with an Avy, 5th, Romic, and Stratos El Jefe, the best shock that will fit on a Bighit Comp is unfortunately Swinger 4 way. The DH on the other hand will fit all of those, some you may have to point the piggyback downwards and towards the back of your bike or use a remote resovoir.