Extensions on cut-outs - Necessary?

I have a set of electric cut-outs that dump before the mufflers.

Would I see better performance out of them if I had a short (say 24") extension attached to them so they don't dump straight after the butterfly valve?

ATM, they are located about 18" down line from the x-pipe, but there is no extension or taper after the actual cut out valve.

Hope this makes sense?