does this need to be changed when going to a bigger line

yes you need to change the pickup tube because if you go from 3/8" to 1/2" line with the same 3/8" pickup tube you will be defeating your purpose check out this website they have a whole sending unit with a 1/2" tube it has a return tube but if your not using the return tube just cap it off heres the site www.robbmcperformance.com hope this helps
jim