If you opt for test, run test enanthate instead of test 400. Enanthate has a similar half-life (to the weighted average for T400), is cheaper per mg of test, and it doesn't hurt.
Im going to have to say your making a mistake if you dont take both...That is if your going to take the deca....I dont know why anyone would take deca alone being it shuts your test down so hard...I would save the money and run both...If not def take the test!