The Tamiya DF-03 option shocks do really need the 2 hole pistons and really thick oil. The shocks on mine are running 50 weight all round I think, compared to my TRF which is running 35 front 25 rear I think. When I was using the stock kit shocks I ran the 2 hole pistons with 70 weight oil!
I like the DF-03 option shocks, I bought 3 sets from JR-RC on ebay and used 1 set on my DF-03, one set on a DT-02 Sand Viper, and one set on a friends Academy SB V2. They all went together with 2 hole pistons and around 40-50 weight oil, and they all work really well.
-Steve