Still working on getting it to boost properly at 2500 but its a work in progress.
Be careful of LSPI . I think that's why there are so many software limits (as mentioned on various forums.)
Have you played around with the auto trans shifting? I reckon that alone would make a big difference on mine- floor it suddenly from a standing start and there seems to be a long hesitation. Then the shifts are very "relaxed" between gears - compared to watching newer torque converter autos on Youtube.
Next step is intercooler, water injection, and very slight intake work.
Have a look at what Mountune did for their MP275 kit on the Focus ST. I've picked up the hardware parts (filter, intake, intercooler) but have only fitted the low restriction intake so far. It's a tight fit but works. It was sold by Ford dealers and covered by the factory warranty - so you know it's a safe and well engineered product.
For most of us in the tuning market, warranty claims become a huge hassle when the dealer denies service basedRead More
dsportmag.com
With the intercoolers, the Mountune MP275 is a thinner "tube and fin" design. Often rubbished compared to thicker "bar and plate" intercoolers, but living in a hot climate I prefer the 2" thin intercooler core as more air will get through to the radiator.
One other thing to consider is apparently the Mk3 Focus RS stock intercooler will fit on the Focus ST- so it should also fit (with some possible custom mounts required). Out of the factory Ford covered up part of it to reduce it's efficiency! Apparently condensation forming inside can be an issue in humid climates if the intercooler works too well.