how restrictive is the original ford downpipe ?

i can see the 4 primaries are a bit short, but it would fit in my application....
how much will it hold the engine back ?

dave

Might fit.

Not as restrictive as most cast manifolds but the headers are extremely short. Around 10" from memory.

But ask yourself this. Ford have a rather huge budget for R+D. Ok, there are restrictions, they want things made cheaply, and the tuning may well be for economy.
However, compare that to how some designs are made. Many seem to be "that looks right".

I would use the factory one and see how it goes. Or do some research and find out what the duratec needs. Dunnel, raceline and a few other places should have suitable offerings? or how about this http://www.racetuners.com/images/duratec/duratec2.jpg or Tony Law himself http://www.tonylawexhausts.co.uk/2410/frames.php

Or do ford offer a "go faster" one similar to the ST170 for the zetec?