If I have a 3" DP connected to a 3" MP, then connected to a 2.5" CB, what does this do to exhaust flow? I ask because I have a HF cat now and am switching to resonated MP. I have N1 duals on now, which I will probably remove due to noise levels. I will put on my old Pettit single tip(for now, until I decide what I really want), but its piping only measured 2.5". Thus causing me to ponder over this size difference.
So, will it mess up the flow? Are most catbacks 2.5"(I'll measure N1 when I remove it)? Would a 3" CB just be too noisy w/ the MP? Does it even matter?

Actually I think the MP is like 2 7/8". Still a difference, though.

Any ideas?

Thanks,
Steve

 

it will create a little back pressure

a 3" pipe is about equal to 4 1.5" pipes a 4" is about equal to 4 2" pipes if that helps. thats also a really rough apporximation

 

is a 5 1/4" gready street performance cat with 3" mid and downpipe good.