would theese things give me i increase in hp in my stock 305tbi(my car has no converters)?
edelbrock performer intake with carb to tbi adapter, new holley 670 cfm throttle body and a set of 305 H.O heads
and can you put headers on with out taking out the motor? and what headers would be best with out re doing my whole exhuast?

 

you can get shorty headers and make a custom y pipe that will connect to your existing exhaust system.
the 416 HO heads will be a improvment over the swirl port heads.do some port work and it will be even better. the performer intake is a good street intake.if you get a bigger TB you should get bigger injectors . and a new tune will be a must
so some gains are to be made.