What engine management are you running? And what sort of power is it making?
Running a Puma ECU flashed with the Racing Puma management (which was mapped by Ahmed Bayjoo) but supplemented by a Unichip which I've been able to have mapped to suit as the car's been developed.
It puts out around 180bhp give or take (depending upon the season!) and has been pretty reliable in that state of tune for around 60k miles, let down only by electrical sensors which this car eats by the bucket load. TPSs and lambdas are its favourite. Mechanically it's got some particularly lumpy cams, had a lot of headwork (the comp. ratio is pretty extreme and, in truth, I've probably skimmed it too much when I was having the head done), and I've spent a fortune getting it to breathe properly, both on the inlet and exhaust side. I've kept it legal though and it still (just!) squeaks through the emissions test at MoT time.
There is a downside though - it's almost all power and the torque figures are pretty disappointing, being little more than the standard Racing Puma (but then I was young(ish) then and thought power was everything).
Mrs. KW had a Fiesta with a 1.25 Zetec SE and I loved that engine. Nice and light, loved to rev. I wonder how much weight I could save by dropping one into the Westfield.
That's the joy of these little Zetecs - they weigh buttons and throttle response is close to immediate; they zip through the revs like a bike (Yamaha were responsible for the engine development so that might help to explain that). That and the handling, of course - as you'll know, even the 1.25 cooking model Fiestas are an absolute hoot.
I'd better just say how much I'm enjoying driving the Omega though else people will think that I'm a Ford nut who's come on here just to bring it down from the inside!!