Should I replace Focus plugs and leads?

I bought an 03 Focus 1.6 about 18 months ago without a service history. We tend to run old bangers into the ground and take pot-luck with
neglecting the servicing, we usually get away with no expensive bills :-).
I'm about to book it in for an MoT and get the oil changed while it's there. I've heard about non-approved plugs and leads damaging the coil pack, but is it also important to change them regularly even if the car's running OK? How much is it likely to cost?
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TH * http://www.realh.co.uk

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On Wed, 16 Jan 2013 14:44:56 +0000, Tony Houghton wrote:

1.8 Zetec? Yes, change them. They're almost a service item on those IME. I think the last set I bought at a dealer was about £48 for leads.
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Mike P

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On Wed, 16 Jan 2013 14:44:56 +0000, Tony Houghton wrote:

The usual failure mode is a slight mis-fire. If ignored, that may damage the coil. Genuine plugs/leads were around 85UKP last time I checked; a coil was 100UKP.
If you are on a shoestring, it would at least be worth removing the plugs to see how worn they are, and re-gapping them (to 1mm).
Chris
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On Wed, 16 Jan 2013 15:36:24 +0000, Chris Whelan wrote:
[...]
Forgot to mention that there are reports that the misfire can kill the ECU, which would possibly render it as an uneconomic repair.
Chris
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If bad leads kill the coil from over work, then yes it can spike the ECU and blow the output drivers. Usual symptom is 2cyl's firing, 2 dead.
Tim..
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