My series 1 zetec turbo project has a 3 inch mongoose exhaust on it, but I have seen someone is making a copy of the original S1 exhaust in stainless steel, but it is not 3 inch diameter, How critical is the 3 inch exhaust when running a zetec turbo engine as I am considering replacing the mongoose with original copy stainless type.

 

Think my mk4 ecort zt only has a 2.5" mongoose system.

If I had a S1 with a zetec turbo I would stick with the mongoose.

 

It would be interesting to see if someone has switched exhausts and seen a difference.

I'm tempted to say stay with the Mongoose (is that 3" all of the way?), but I have been eyeing up that copy system as well, just to aid the sleeper look, well, you know what I mean .

 

I think that bloke makes them to order, anyway, so you could specify a 3 inch bore, surely? If not, I'm sure I read somewhere that only the downpipe needs to be 3inch and the rest of the system is fine at 2.5 upto around 350/400bhp..? Might be wrong, but that's in my head for some reason

 

Yeah it depends on your power level, I don't know exactly when a 2.5" becomes restrictive but I bet it's more than enough for most.