hey if your going for all out but want to keep the 420a engine hahnrace craft has turbos for it.
http://www.hahnracecraft.com then id get an intake and exausht at the same time. Thats just my thoughts if you dont want to drop the money for a turbo Id get the intake and exausht and maybe save for the turbo. Also id wait for like body kits till you got the engine running strong.