If you use an aftermarket y-pipe with high flow cats to a 3” single midpipe, does this reduce the performance compared to duals with an x pipe?

Start with a lot more info. If you’re NA chances are a single 3” will flow all you need.

Ok thanks. Yes, just NA. I currently have a 3” catback midpipe to a MagnaFlow bullet then split to 2.5” duals. I didn’t think I’d want headers when I did the original exhaust but now that I do, I’d like to keep what I’ve got if it won’t work against any performance improvements from the headers and aftermarket y-pipe. If duals and an x-pipe are substantially better I can probably get some of my money back by selling the catback system

A big single works too. 3.5 or 4” will flow a hell of a lot.

still have the stock one. I assume I would need an aftermarket one to fit up with the headers. My midpipe is 3” and is currently the stock length, but I can Chang it cheap to whatever length would fit the aftermarket one. I’ve still got the stock resonator in to tame the straight through muffler but will swap out to a 3” resonator when I do the headers and new y-pipe.

Do green catted y-pipes flow better than the stock y-pipe?