Fitment problems and backpressure question, cutout, need some quick help
 

I think the place I ordered my Flowtech cutout from sent me the wrong size. The box says its for anything from 2 1/2" to 3" systems, however it is noticeable smaller than the Y-pipe outlet and of course again smaller than the intermediate pipe. It will be going after the cat on the passenger side, I want to install the cutout and then bolt on the electric butterfly valve after the pipe is on. (the components are separate, I bought the QTEC valve used, had to buy the cutout pipe). Should I get some sort of reducer to adapt to both ends of the cutout where it meets the intermediate and y-pipes?? Will that restrict or hinder flow having the flow go from 3" to 2 1/2" then back to 3" again?? Right now I have already removed the stock intermediate pipe and having been running most certainly "wide" for a couple of weeks now. Any help would be appreciated. Also, any people out there with cutouts or running wide worry about backpressure problems.?

thanks

I would get a 3" cutout.