quick question
 

first off, i am pretty new to tuning so i got a lot to learn. so heres my question: if i get a turbo kit upgrade like from greddy, do i need a boost controller(http://www.greddy.com/prod_proftype-s.htm) and ecu(http://www.greddy.com/prod_e_manage_ult.htm)? should i get them even if i stick with the stock turbo? also, what are they for and what do they do?