Hey there, welcome to FocusCanada.net!
We're a little abrasive here at times, but overall there's a real sense of concern for each other... helping out with mod ideas, suggestions and some guys even give a hand with installs the odd time.
We also have a decent parts sponsor in ZX3Tuning.com - he has access to a LOT of stuff.
As for the SPI, I recall getting a definite NO about the Zetec internals.
Really, the SPI is a great dual-mode motor if you mod it correctly... it remains efficient around town and it'll pull its weight on the highway/track as required thanks to the split-runner intake manifold.
Good opener mods are a true catalytic-back exhaust, a decent intake (anything for a Zetec will fit if you have a basic rubber reducer, measure your TB first to get the lower size right, then measure the intake tubing... it should be about 3") with some sort of a washable / cleanable filter, ensuring you have 8mm wires on the SPI, etc.
After that, you have more options - none of which is "easy", except for one - the underdrive pulley. The SPI gets a choice of a 25% or 50% underdrive crank pulley from the guys at
http://www.escortfocus.com. The belt sizing gets hairy, depending on the year of your SPI and whether or not you have A/C. I'd suggest buying belts in 1/2" increments up to 3" in either direction from the size they suggest at escortfocus.com and then returning what you don't need. The UDP is a great addition as it really wakes up the motor and frees up a fair amount of punch (for the SPI, anyways).
Other options are custom-ground or package-ground cams from escortfocus.com, SCT calibration via a SuperChips Tuning ECU chip or XCalibrator/2 programmer. That little jewel will also read trouble codes that the PCM throws.
An oddity is that no forced-induction kits exist specifically for the SPI. On that note, NO Powerworks kits will fit the SPI because of the fact that they replace the intake manifold on the Zetec and SVT Foci... and those manifolds are not compatible with our engine. A number of guys in the States have made their own turbo kits, and more than a few guys here can give you technical advice on building your own as they're pretty experienced. However, my best advice is to mod it lightly at first, in stages and to stay away from big buildups if the car is a daily driver.
An definite point of interest is that if your car doesn't have a tachometer, any Zetec-powered Focus (even the SVT) dash can be installed directly in place with no ill effects. However, the MTO requires that you record the KMs on the old gauge cluster when you remove it and the new KMs when you install it. Calculate the difference and then remember that each year when you renew your plates. It's also a legal obligation when you sell the car.
Check out my Cardomain link in my sig if you want to see what I've done with our SPI-powered sedan.
Again, welcome to FocusCanada.net. :D :hi: