Dp to cat with reducers?

[dcpppf]

I currently have an apr dp to stock cat. Looking at buying eurojet cat locally. The seller doesn't have the j pipe, and his current setup is an apr dp with reducer to the eurojet with a reducer... Essentially my setup would be the exact same but my question is if I'm missing out on anything by using the reducers as opposed to the j pipe.

 

[dcpppf]

Cause essentially there is a 2.5" pinch point where the reducers connect, and all else is 3"