i just recently bought all my items for my exhaust (excluding the pipping itself), i bought a DC sports 4-2-1 header, magnaflow caty, magnaflow muffler and magnaflow tip.
trouble is i bought the magnaflow items with 2.5" inlets and outlets. the dc sports header has an outlet of 2". what i was intentionally wanting to do is a 2.5" pipping exhaust system.
But now i'm not so sure, can i go with 2.25" pipping instead and increase the backpressure? would that work? i just think that will be kinda goofy in a way (2.25" pipping going into a 2.5" inlet then out to a 2.25" pipping then into another 2.5" inlet, and so on)
please help. i have a lil bit of time to decide on whats going on, since my car is in the body shop.

EDIT: i'm running a 1.6ltr sohc zc in my car.