If you want to make NA horse power, you have to raise the rev limit so in my opinion a chip to raise the rev limiter is necessary to take advantage of cams, and your headwork all of which is going to peak at above 7K rpm.
The ZX1 does not care to live at 7K+ so ARP rod bolts are necessary to keep the rods together.
The focus guys are doing more because the ZX3 aftermarket for their version is hot with products.
Those of us with ZX1 have to import Mondeo pre '98 stuff from the UK which was very expensive even before the dollar died.
The ZX1 intake manifold is a killjoy for mods. Breathing enhancements are not going to work unless this pos is removed for a different version.
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