I plan on keeping my 05 EVO's bottom end and head stock, and plan on adding AEM EMS, 3" TBE, Buschurs Race FMIC, Walboro 255lph FP, Camgears, 780CC injectors, alchy injection, ARP headstuds and some cams, either HKS 280's or 272's.

Which one would yield more power? be better to get? be more reliable?

 

Try 272's IMHO, you are only running a 50 Trim and you don't want to totally kill your bottom end.

 

If set up correctly the 280s will not lose ANY midrange. Do a search, David Buschur has done many dyno tests with them and saw great results, cam gears are a must! They didnt lose ANY mid range on the STOCK TURBO!