y7 exhaust mani vs the y8
 

Ok so I was wondering if there is a difference between the two?

And if the y8 will fit the y7 head?

Aslo the y8 has the cat bolted to the mani right not like the y7s which is one big piece

yes the y8 is a 4-2-1 design, the y7 is a 4-1, if ya wanna do it with out welding and cutting shit, just run the whole ex, or D16y8 in other words exhaust system. better low end, but not much.

oh yeah, yes BOTH manifolds will bolt to the head without a problems.

The Y7 is fucking gay, no lie, it will rob any singlecam of bottom end torque and HP, and it chokes the shit out of engine when you get into higher gears/speeds which kills you Top End: Due to the fact that right when exhaust gases exit the combustion chamber they are being stopped by a heavily restrictive cat.
The Y8 Header is slightly better because it allows a little more exhaust flow which can improve bottom end response.

If youre doing a mild NA build for a sohc I would just recommend some sort of aftermarket Header with a Highflow cat or test pipe. Should let it breathe a little better bottom to top.

And just like ejpusha said they both bolt right up to each other.

Wr is the cat on the y8 and wr do both of the o2 sensors on my y7 one is at the top by the head and the other is after the cat im asking cuz I never payed attention to the y8 mani and I need to go threw emission soon

i swapped a y8 into my coupe, but i used the y7 manifold so i could get my exhaust made because a shop wouldnt touch my car without a cat. the y7 manifold felt like my car had absolutely no top-end

On the D16Y8 Coupes, there is one O2 sensor located on the stock header piece in one of the runners I believe, and there is one located after the catalytic converter (underneath the car).
Y7 are basically the same, one right on top of the cat/header then one right under the cat still in the header piece.

just do what i said run the full D16y8 exhaust, all you will have to do is lengthen four wires witch go to your o2 sensor. if you do that it will be completely legal.

I think that's wat ima do

Aren't the exhaust from the coupe and hatch slightly different. the way they are routed front to back I mean?

Heres what you do, assuming you have a Hatch.
Put the D16Y8 Exhaust Manifold, Catalytic converter, and Midpipe (Exhaust pipe from cat to rear axle). And just use your muffler from your hatch. Everything should be completely legal.

^^^^^ cool and I do have a hatch

that is what i did but i used a megan header and magnaflow cat