I use the Berkley Bullet Pop 70mm and they come stock with size 5 hooks including the feathered treble. When I replace them would it weigh it down too much replacing them both with size 4 one of which being the feathered treble?

No, it will be fine.  They are extremely buoyant.

 

If the hooks interfere with each other, going to a short shank hook when up-sizing hooks usually solves that problem.  

Just now, rtwvumtneer6 said:

No, it will be fine.  They are extremely buoyant.

 

If the hooks interfere with each other, going to a short shank hook when up-sizing hooks usually solves that problem.  

Ok right on. I didnt want to buy a size 5 set of hooks specifically for these popper. I'd rather just get size 4 and it be more universal.

Not a problem - the size difference isn't that much. I've put #6 hooks on when having to replace #7s and there wasn't a problem. I've even put #1s on a lure that originally had #2s and it wasn't an issue either. So long as you don't go too far from the original size, go right ahead.

1 minute ago, MN Fisher said:

Not a problem - the size difference isn't that much. I've put #6 hooks on when having to replace #7s and there wasn't a problem. I've even put #1s on a lure that originally had #2s and it wasn't an issue either. So long as you don't go too far from the original size, go right ahead.

Awesome! I wasn't wanting to buy a random pack of #5 just for 2 poppers. I'd rather keep stock of #4 and #6 and just use those if possible.